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  • 1. Agogo, George O.
    et al.
    van der Voet, Hilko
    van 't Veer, Pieter
    Ferrari, Pietro
    Muller, David C.
    Sanchez-Cantalejo, Emilio
    Bamia, Christina
    Braaten, Tonje
    Knuppel, Sven
    Johansson, Ingegerd
    Umeå University, Faculty of Medicine, Department of Odontology.
    van Eeuwijk, Fred A.
    Boshuizen, Hendriek C.
    A method for sensitivity analysis to assess the effects of measurement error in multiple exposure variables using external validation data2016In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 16, article id 139Article in journal (Refereed)
    Abstract [en]

    Background: Measurement error in self-reported dietary intakes is known to bias the association between dietary intake and a health outcome of interest such as risk of a disease. The association can be distorted further by mismeasured confounders, leading to invalid results and conclusions. It is, however, difficult to adjust for the bias in the association when there is no internal validation data. Methods: We proposed a method to adjust for the bias in the diet-disease association (hereafter, association), due to measurement error in dietary intake and a mismeasured confounder, when there is no internal validation data. The method combines prior information on the validity of the self-report instrument with the observed data to adjust for the bias in the association. We compared the proposed method with the method that ignores the confounder effect, and with the method that ignores measurement errors completely. We assessed the sensitivity of the estimates to various magnitudes of measurement error, error correlations and uncertainty in the literature-reported validation data. We applied the methods to fruits and vegetables (FV) intakes, cigarette smoking (confounder) and all-cause mortality data from the European Prospective Investigation into Cancer and Nutrition study. Results: Using the proposed method resulted in about four times increase in the strength of association between FV intake and mortality. For weakly correlated errors, measurement error in the confounder minimally affected the hazard ratio estimate for FV intake. The effect was more pronounced for strong error correlations. Conclusions: The proposed method permits sensitivity analysis on measurement error structures and accounts for uncertainties in the reported validity coefficients. The method is useful in assessing the direction and quantifying the magnitude of bias in the association due to measurement errors in the confounders.

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  • 2.
    Audulv, Åsa
    et al.
    Umeå University, Faculty of Medicine, Department of Nursing.
    Hall, Elisabeth O. C.
    Faculty of Health, Aarhus University, Aarhus, Denmark; Faculty of Health Sciences, University of Faroe Islands, Faroe Islands, Thorshavn, Denmark.
    Kneck, Åsa
    Department of Health Care Sciences, Ersta Sköndal Bräcke University College, Stockholm, Sweden.
    Westergren, Thomas
    Department of Health and Nursing Science, University of Agder, Kristiansand, Norway; Department of Public Health, University of Stavanger, Stavanger, Norway.
    Fegran, Liv
    Department of Health and Nursing Science, University of Agder, Kristiansand, Norway.
    Pedersen, Mona Kyndi
    Center for Clinical Research, North Denmark Regional Hospital, Hjørring, Denmark; Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
    Aagaard, Hanne
    Lovisenberg Diaconale Univeristy of College, Oslo, Norway.
    Dam, Kristianna Lund
    Faculty of Health Sciences, University of Faroe Islands, Faroe Islands, Thorshavn, Denmark.
    Ludvigsen, Mette Spliid
    Department of Clinical Medicine-Randers Regional Hospital, Aarhus University, Aarhus, Denmark; Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway.
    Qualitative longitudinal research in health research: a method study2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, no 1, article id 255Article, review/survey (Refereed)
    Abstract [en]

    Background: Qualitative longitudinal research (QLR) comprises qualitative studies, with repeated data collection, that focus on the temporality (e.g., time and change) of a phenomenon. The use of QLR is increasing in health research since many topics within health involve change (e.g., progressive illness, rehabilitation). A method study can provide an insightful understanding of the use, trends and variations within this approach. The aim of this study was to map how QLR articles within the existing health research literature are designed to capture aspects of time and/or change.

    Methods: This method study used an adapted scoping review design. Articles were eligible if they were written in English, published between 2017 and 2019, and reported results from qualitative data collected at different time points/time waves with the same sample or in the same setting. Articles were identified using EBSCOhost. Two independent reviewers performed the screening, selection and charting.

    Results: A total of 299 articles were included. There was great variation among the articles in the use of methodological traditions, type of data, length of data collection, and components of longitudinal data collection. However, the majority of articles represented large studies and were based on individual interview data. Approximately half of the articles self-identified as QLR studies or as following a QLR design, although slightly less than 20% of them included QLR method literature in their method sections.

    Conclusions: QLR is often used in large complex studies. Some articles were thoroughly designed to capture time/change throughout the methodology, aim and data collection, while other articles included few elements of QLR. Longitudinal data collection includes several components, such as what entities are followed across time, the tempo of data collection, and to what extent the data collection is preplanned or adapted across time. Therefore, there are several practices and possibilities researchers should consider before starting a QLR project.

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  • 3.
    Audulv, Åsa
    et al.
    Umeå universitet.
    Hall, Elisabeth O. C.
    Aarhus University, Denmark; University of Faroe Islands, Denmark.
    Kneck, Åsa
    Marie Cederschiöld University, Department of Health Care Sciences.
    Westergren, Thomas
    University of Agder, Norway; University of Stavanger, Norway.
    Fegran, Liv
    University of Agder, Norway.
    Pedersen, Mona Kyndi
    North Denmark Regional Hospital, Denmark; Aalborg University, Denmark.
    Aagaard, Hanne
    Lovisenberg Diaconale Univeristy of College, Norway.
    Dam, Kristianna Lund
    University of Faroe Islands, Denmark.
    Ludvigsen, Mette Spliid
    Aarhus University, Denmark; Nord University, Norway.
    Qualitative longitudinal research in health research: A method study2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, no 1, article id 255Article, review/survey (Refereed)
    Abstract [en]

    Background: Qualitative longitudinal research (QLR) comprises qualitative studies, with repeated data collection, that focus on the temporality (e.g., time and change) of a phenomenon. The use of QLR is increasing in health research since many topics within health involve change (e.g., progressive illness, rehabilitation). A method study can provide an insightful understanding of the use, trends and variations within this approach. The aim of this study was to map how QLR articles within the existing health research literature are designed to capture aspects of time and/or change.

    Methods: This method study used an adapted scoping review design. Articles were eligible if they were written in English, published between 2017 and 2019, and reported results from qualitative data collected at different time points/time waves with the same sample or in the same setting. Articles were identified using EBSCOhost. Two independent reviewers performed the screening, selection and charting.

    Results: A total of 299 articles were included. There was great variation among the articles in the use of methodological traditions, type of data, length of data collection, and components of longitudinal data collection. However, the majority of articles represented large studies and were based on individual interview data. Approximately half of the articles self-identified as QLR studies or as following a QLR design, although slightly less than 20% of them included QLR method literature in their method sections.

    Conclusions: QLR is often used in large complex studies. Some articles were thoroughly designed to capture time/change throughout the methodology, aim and data collection, while other articles included few elements of QLR. Longitudinal data collection includes several components, such as what entities are followed across time, the tempo of data collection, and to what extent the data collection is preplanned or adapted across time. Therefore, there are several practices and possibilities researchers should consider before starting a QLR project.

  • 4.
    Audulv, Åsa
    et al.
    Umeå University, Faculty of Medicine, Department of Nursing.
    Westergren, Thomas
    Department of Health and Nursing Science, University of Agder, Kristiansand, Norway; Department of Public Health, University of Stavanger, Stavanger, Norway.
    Ludvigsen, Mette Spliid
    Department of Clinical Medicine, Randers Regional Hospital, Aarhus University, Aarhus, Denmark; Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway.
    Pedersen, Mona Kyndi
    Centre for Clinical Research, North Denmark Regional Hospital, Hjørring, Denmark; Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
    Fegran, Liv
    Department of Health and Nursing Science, University of Agder, Kristiansand, Norway.
    Hall, Elisabeth O. C.
    Faculty of Health, Aarhus University, Aarhus, Denmark; Faculty of Health Sciences and Nursing, University of Faroe Islands, Torshavn, Faroe Islands.
    Aagaard, Hanne
    Lovisenberg Diaconal University College, Oslo, Norway.
    Robstad, Nastasja
    Department of Health and Nursing Science, University of Agder, Kristiansand, Norway.
    Kneck, Åsa
    Department of Health Care Sciences, Marie Cederschöld University, Stockholm, Sweden.
    Time and change: a typology for presenting research findings in qualitative longitudinal research2023In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 23, no 1, article id 284Article in journal (Refereed)
    Abstract [en]

    Background: Qualitative longitudinal research (QLR) is an emerging methodology used in health research. The method literature states that the change in a phenomenon through time should be the focus of any QLR study, but in empirical studies, the analysis of changes through time is often poorly described, and the emphasis on time/change in the findings varies greatly. This inconsistency might depend on limitations in the existing method literature in terms of describing how QLR studies can present findings. The aim of this study was to develop and describe a typology of alternative approaches for integrating time and/or change in QLR findings.

    Methods: In this method study, we used an adapted scoping review design. Articles were identified using EBSCOhost. In total, methods and results sections from 299 QLR articles in the field of health research were analyzed with inspiration from content analysis.

    Results: We constructed a typology of three types and seven subtypes. The types were based on the underlying structural principles of how time/change was presented: Type A) Findings have a low utilization of longitudinal data, Type B) Findings are structured according to chronological time, and Type C) Findings focus on changes through time. These types differed in 1) the way the main focus was on time, change or neither; 2) the level of interpretation in the findings; and 3) how theoretical understandings of time/change were articulated in the articles. Each type encompassed two or three subtypes that represented distinct approaches to the aim and results presentation of QLR findings.

    Conclusions: This method study is the first to describe a coherent and comprehensive typology of alternative approaches for integrating time/change into QLR findings in health research. By providing examples of various subtypes that can be used for results presentations, it can help researchers make informed decisions suitable to their research intent.

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  • 5.
    Audulv, Åsa
    et al.
    Department of Nursing, Umeå University, Umeå, Sweden.
    Westergren, Thomas
    Department of Health and Nursing Science, University of Agder, Kristiansand, Norway; Department of Public Health, University of Stavanger, Stavanger, Norway.
    Ludvigsen, Mette Spliid
    Department of Clinical Medicine, Randers Regional Hospital, Aarhus University, Aarhus, Denmark; Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway.
    Pedersen, Mona Kyndi
    Centre for Clinical Research, North Denmark Regional Hospital, Hjørring, Denmark; Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
    Fegran, Liv
    Department of Health and Nursing Science, University of Agder, Kristiansand, Norway.
    Hall, Elisabeth O. C.
    Faculty of Health, Aarhus University, Aarhus, Denmark; Faculty of Health Sciences and Nursing, University of Faroe Islands, Torshavn, Faroe Islands.
    Aagaard, Hanne
    Lovisenberg Diaconal University College, Oslo, Norway.
    Robstad, Nastasja
    Department of Health and Nursing Science, University of Agder, Kristiansand, Norway.
    Kneck, Åsa
    Marie Cederschiöld University, Department of Health Care Sciences. Marie Cederschiöld högskola.
    Time and change: A typology for presenting research findings in qualitative longitudinal research2023In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 23, article id 284Article in journal (Refereed)
    Abstract [en]

    Background Qualitative longitudinal research (QLR) is an emerging methodology used in health research. The method literature states that the change in a phenomenon through time should be the focus of any QLR study, but in empirical studies, the analysis of changes through time is often poorly described, and the emphasis on time/change in the findings varies greatly. This inconsistency might depend on limitations in the existing method literature in terms of describing how QLR studies can present findings. The aim of this study was to develop and describe a typology of alternative approaches for integrating time and/or change in QLR findings.

    Methods In this method study, we used an adapted scoping review design. Articles were identified using EBSCOhost. In total, methods and results sections from 299 QLR articles in the field of health research were analyzed with inspiration from content analysis.

    Results We constructed a typology of three types and seven subtypes. The types were based on the underlying structural principles of how time/change was presented: Type A) Findings have a low utilization of longitudinal data, Type B) Findings are structured according to chronological time, and Type C) Findings focus on changes through time. These types differed in 1) the way the main focus was on time, change or neither; 2) the level of interpretation in the findings; and 3) how theoretical understandings of time/change were articulated in the articles. Each type encompassed two or three subtypes that represented distinct approaches to the aim and results presentation of QLR findings.

    Conclusions This method study is the first to describe a coherent and comprehensive typology of alternative approaches for integrating time/change into QLR findings in health research. By providing examples of various subtypes that can be used for results presentations, it can help researchers make informed decisions suitable to their research intent.

  • 6.
    Axén, Iben
    et al.
    Institute of Environmental Medicine, Unit of Intervention and Implementation Research in Worker Health, Karolinska Institutet, Stockholm, Sweden.
    Bodin, Lennart
    Institute of Environmental Medicine, Unit of Intervention and Implementation Research in Worker Health, Karolinska Institutet, Stockholm, Sweden.
    Searching for the optimal measuring frequency in longitudinal studies: an example utilizing short message service (SMS) to collect repeated measures among patients with low back pain2016In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 16, no 1, article id 119Article in journal (Refereed)
    Abstract [en]

    Background: Mobile technology has opened opportunities within health care and research to allow for frequent monitoring of patients. This has given rise to detailed longitudinal information and new insights concerning behaviour and development of conditions over time.

    Responding to frequent questionnaires delivered through mobile technology has also shown good compliance, far exceeding that of traditional paper questionnaires. However, to optimize compliance, the burden on the subjects should be kept at a minimum.

    In this study, the effect of using fewer data points compared to the full data set was examined, assuming that fewer measurements would lead to better compliance.

    Method: Weekly text-message responses for 6 months from subjects recovering from an episode of low back pain (LBP) were available for this secondary analysis. Most subjects showed a trajectory with an initial improvement and a steady state thereafter.

    The data were originally used to subgroup (cluster) patients according to their pain trajectory. The resulting 4-cluster solution was compared with clusters obtained from five datasets with fewer data-points using Kappa agreement as well as inspection of estimated pain trajectories. Further, the relative risk of experiencing a day with bothersome pain was compared week by week to show the effects of discarding some weekly data.

    Results: One hundred twenty-nine subjects were included in this analysis. Using data from every other weekly measure had the highest agreement with the clusters from the full dataset, weighted Kappa = 0.823. However, the visual description of pain trajectories favoured using the first 18 weekly measurements to fully capture the phases of improvement and steady-state. The weekly relative risks were influenced by the pain trajectories and 18 weeks or every other weekly measure were the optimal designs, next to the full data set.

    Conclusions: A population recovering from an episode of LBP could be described using every other weekly measurement, an option which requires fewer weekly measures than measuring weekly for 18 weeks. However a higher measuring frequency might be needed in the beginning of a clinical course to fully map the pain trajectories.

  • 7.
    Axén, Iben
    et al.
    Institute of Environmental Medicine, Unit of Intervention and Implementation Research, Karolinska Institutet, Stockholm, Sweden.
    Bodin, Lennart
    Institute of Environmental Medicine, Unit of Intervention and Implementation Research, Karolinska Institutet, Stockholm, Sweden.
    Kongsted, Alice
    Clinical Locomotion Network, Nordic Institute of Chiropractic and Clinical Biomechanics, Odense, Denmark.
    Wedderkopp, Niels
    Institute of Regional Health Services Research, University of Southern Denmark, Odense, Denmark.
    Jensen, Irene
    Institute of Environmental Medicine, Unit of Intervention and Implementation Research, Karolinska Institutet, Stockholm, Sweden.
    Bergström, Gunnar
    Institute of Environmental Medicine, Unit of Intervention and Implementation Research, Karolinska Institutet, Stockholm, Sweden.
    Analyzing repeated data collected by mobile phones and frequent text messages: An example of Low back pain measured weekly for 18 weeks2012In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 12, article id 105Article in journal (Refereed)
    Abstract [en]

    Background: Repeated data collection is desirable when monitoring fluctuating conditions. Mobile phones can be used to gather such data from large groups of respondents by sending and receiving frequently repeated short questions and answers as text messages.

    The analysis of repeated data involves some challenges. Vital issues to consider are the within-subject correlation, the between measurement occasion correlation and the presence of missing values.

    The overall aim of this commentary is to describe different methods of analyzing repeated data. It is meant to give an overview for the clinical researcher in order for complex outcome measures to be interpreted in a clinically meaningful way.

    Methods: A model data set was formed using data from two clinical studies, where patients with low back pain were followed with weekly text messages for 18 weeks. Different research questions and analytic approaches were illustrated and discussed, as well as the handling of missing data. In the applications the weekly outcome “number of days with pain” was analyzed in relation to the patients’ “previous duration of pain” (categorized as more or less than 30 days in the previous year).

    Research questions with appropriate analytical methods

    1: How many days with pain do patients experience? This question was answered with data summaries.

    2: What is the proportion of participants “recovered” at a specific time point? This question was answered using logistic regression analysis.

    3: What is the time to recovery? This question was answered using survival analysis, illustrated in Kaplan-Meier curves, Proportional Hazard regression analyses and spline regression analyses.

    4: How is the repeatedly measured data associated with baseline (predictor) variables? This question was answered using generalized Estimating Equations, Poisson regression and Mixed linear models analyses.

    5: Are there subgroups of patients with similar courses of pain within the studied population?A visual approach and hierarchical cluster analyses revealed different subgroups using subsets of the model data.

    Conclusions: We have illustrated several ways of analysing repeated measures with both traditional analytic approaches using standard statistical packages, as well as recently developed statistical methods that will utilize all the vital features inherent in the data.

  • 8.
    Bergman, Patrick
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Medicine and Optometry. Linnaeus University, Linnaeus Knowledge Environments, Sustainable Health.
    Hagströmer, Maria
    Karolinska institutet, Sweden;Karolinska University Hospital, Sweden;Sophiahemmet university, Sweden.
    No one accelerometer-based physical activity data collection protocol can fit all research questions.2020In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 20, no 1, p. 1-8, article id 141Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Measuring physical activity and sedentary behavior accurately remains a challenge. When describing the uncertainty of mean values or when making group comparisons, minimising Standard Error of the Mean (SEM) is important. The sample size and the number of repeated observations within each subject influence the size of the SEM. In this study we have investigated how different combinations of sample sizes and repeated observations influence the magnitude of the SEM.

    METHODS: A convenience sample were asked to wear an accelerometer for 28 consecutive days. Based on the within and between subject variances the SEM for the different combinations of sample sizes and number of monitored days was calculated.

    RESULTS: Fifty subjects (67% women, mean ± SD age 41 ± 19 years) were included. The analyses showed, independent of which intensity level of physical activity or how measurement protocol was designed, that the largest reductions in SEM was seen as the sample size were increased. The same magnitude in reductions to SEM was not seen for increasing the number of repeated measurement days within each subject.

    CONCLUSION: The most effective way of reducing the SEM is to have a large sample size rather than a long observation period within each individual. Even though the importance of reducing the SEM to increase the power of detecting differences between groups is well-known it is seldom considered when developing appropriate protocols for accelerometer based research. Therefore the results presented herein serves to highlight this fact and have the potential to stimulate debate and challenge current best practice recommendations of accelerometer based physical activity research.

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  • 9. Bergman, Patrick
    et al.
    Hagströmer, Maria
    Sophiahemmet University.
    No one accelerometer-based physical activity data collection protocol can fit all research questions2020In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 20, no 1, article id 141Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Measuring physical activity and sedentary behavior accurately remains a challenge. When describing the uncertainty of mean values or when making group comparisons, minimising Standard Error of the Mean (SEM) is important. The sample size and the number of repeated observations within each subject influence the size of the SEM. In this study we have investigated how different combinations of sample sizes and repeated observations influence the magnitude of the SEM.

    METHODS: A convenience sample were asked to wear an accelerometer for 28 consecutive days. Based on the within and between subject variances the SEM for the different combinations of sample sizes and number of monitored days was calculated.

    RESULTS: Fifty subjects (67% women, mean ± SD age 41 ± 19 years) were included. The analyses showed, independent of which intensity level of physical activity or how measurement protocol was designed, that the largest reductions in SEM was seen as the sample size were increased. The same magnitude in reductions to SEM was not seen for increasing the number of repeated measurement days within each subject.

    CONCLUSION: The most effective way of reducing the SEM is to have a large sample size rather than a long observation period within each individual. Even though the importance of reducing the SEM to increase the power of detecting differences between groups is well-known it is seldom considered when developing appropriate protocols for accelerometer based research. Therefore the results presented herein serves to highlight this fact and have the potential to stimulate debate and challenge current best practice recommendations of accelerometer based physical activity research.

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  • 10.
    Besancon, Lonni
    et al.
    Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, Faculty of Science & Engineering. Monash Univ, Australia.
    Peiffer-Smadja, Nathan
    Univ Paris, France; Imperial Coll London, England.
    Segalas, Corentin
    London Sch Hyg & Trop Med, England.
    Jiang, Haiting
    Nanjing Med Univ, Peoples R China.
    Masuzzo, Paola
    Inst Globally Distributed Open Res & Educ, Sweden.
    Smout, Cooper
    Inst Globally Distributed Open Res & Educ, Sweden.
    Billy, Eric
    Strasbourg, France.
    Deforet, Maxime
    Sorbonne Univ, France.
    Leyrat, Clemence
    London Sch Hyg & Trop Med, England; London Sch Hyg & Trop Med, England.
    Open science saves lives: lessons from the COVID-19 pandemic2021In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 21, no 1, article id 117Article in journal (Other academic)
    Abstract [en]

    In the last decade Open Science principles have been successfully advocated for and are being slowly adopted in different research communities. In response to the COVID-19 pandemic many publishers and researchers have sped up their adoption of Open Science practices, sometimes embracing them fully and sometimes partially or in a sub-optimal manner. In this article, we express concerns about the violation of some of the Open Science principles and its potential impact on the quality of research output. We provide evidence of the misuses of these principles at different stages of the scientific process. We call for a wider adoption of Open Science practices in the hope that this work will encourage a broader endorsement of Open Science principles and serve as a reminder that science should always be a rigorous process, reliable and transparent, especially in the context of a pandemic where research findings are being translated into practice even more rapidly.

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  • 11.
    Carlsson, Jessica
    et al.
    Örebro University, School of Medical Sciences. Örebro University Hospital. Department of Urology.
    Davidsson, Sabina
    Örebro University, School of Medical Sciences. Department of Urology, Faculty of Medicine and Health, University Hospital, Örebro, Sweden.
    Fridfeldt, Jonna
    Department of Urology, Faculty of Medicine and Health, University Hospital Örebro, Örebro, Sweden; Örebro University, Örebro, Sweden.
    Giunchi, Francesca
    Department of Pathology, F. Addari Institute of Oncology S. Orsola Hospital, Bologna, Italy.
    Fiano, Valentina
    Cancer Epidemiology Unit-CERMS, Department of Medical Sciences, University of Turin and CPO-Piemonte, Turin, Italy.
    Grasso, Chiara
    Cancer Epidemiology Unit-CERMS, Department of Medical Sciences, University of Turin and CPO-Piemonte, Turin, Italy.
    Zelic, Renata
    Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institute, Stockholm, Sweden.
    Richiardi, Lorenzo
    Cancer Epidemiology Unit-CERMS, Department of Medical Sciences, University of Turin and CPO-Piemonte, Turin, Italy.
    Andrén, Ove
    Örebro University, School of Medical Sciences. Department of Urology, Faculty of Medicine and Health, University Hospital Örebro, Örebro, Sweden.
    Pettersson, Andreas
    Clinical Epidemiology Unit, Department of Medicine Solna, Karolinska Institute, Stockholm, Sweden.
    Fiorentino, Michelangelo
    Department of Pathology, F. Addari Institute of Oncology S. Orsola Hospital, Bologna, Italy.
    Akre, Olof
    Department of Medicine Solna, Karolinska Institute, and Department of Urology, Karolinska University Hospital, Stockholm, Sweden.
    Quantity and quality of nucleic acids extracted from archival formalin fixed paraffin embedded prostate biopsies2018In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 18, no 1, article id 161Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: In Sweden, human tissue samples obtained from diagnostic and surgical procedures have for decades been routinely stored in a formalin-fixed, paraffin-embedded, form. Through linkage with nationwide registers, these samples are available for molecular studies to identify biomarkers predicting mortality even in slow-progressing prostate cancer. However, tissue fixation causes modifications of nucleic acids, making it challenging to extract high-quality nucleic acids from formalin fixated tissues.

    METHODS: In this study, the efficiency of five commercial nucleic acid extraction kits was compared on 30 prostate biopsies with normal histology, and the quantity and quality of the products were compared using spectrophotometry and Agilent's BioAnalyzer. Student's t-test's and Bland-Altman analyses were performed in order to investigate differences in nucleic acid quantity and quality between the five kits. The best performing extraction kits were subsequently tested on an additional 84 prostate tumor tissues. A Spearman's correlation test and linear regression analyses were performed in order to investigate the impact of tissue age and amount of tissue on nucleic acid quantity and quality.

    RESULTS: Nucleic acids extracted with RNeasy® FFPE and QIAamp® DNA FFPE Tissue kit had the highest quantity and quality, and was used for extraction from 84 tumor tissues. Nucleic acids were successfully extracted from all biopsies, and the amount of tumor (in millimeter) was found to have the strongest association with quantity and quality of nucleic acids.

    CONCLUSIONS: To conclude, this study shows that the choice of nucleic acid extraction kit affects the quantity and quality of extracted products. Furthermore, we show that extraction of nucleic acids from archival formalin-fixed prostate biopsies is possible, allowing molecular studies to be performed on this valuable sample collection.

  • 12.
    De Costa, Ayesha
    et al.
    Karolinska Institutet.
    Shet, Anita
    St Johns Colege, Bangalore.
    Kumarasamy, N
    YRG Care, Madras.
    Ashorn, Per
    Åbo University.
    Eriksson, Bo
    Nordic School of Public Health.
    Bogg, Lennart
    Diwan, Vinod
    Karolinska Institutet.
    Design of a randomized trial to evaluate the influence of mobile phone reminders on adherence to first line antiretroviral treatment in South India: the HIVIND study protocol2010In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 10, no 25Article in journal (Refereed)
    Abstract [en]

    Poor adherence to antiretroviral treatment has been a public health challenge associated with the treatment of HIV. Although different adherence-supporting interventions have been reported, their long term feasibility in low income settings remains uncertain. Thus, there is a need to explore sustainable contextual adherence aids in such settings, and to test these using rigorous scientific designs. The current ubiquity of mobile phones in many resource-constrained settings, make it a contextually appropriate and relatively low cost means of supporting adherence. In India, mobile phones have wide usage and acceptability and are potentially feasible tools for enhancing adherence to medications. This paper presents the study protocol for a trial, to evaluate the influence of mobile phone reminders on adherence to first-line antiretroviral treatment in South India.

    Methods/Design: 600 treatment naive patients eligible for first-line treatment as per the national antiretroviral treatment guidelines will be recruited into the trial at two clinics in South India. Patients will be randomized into control and intervention arms. The control arm will receive the standard of care; the intervention arm will receive the standard of care plus mobile phone reminders. Each reminder will take the form of an automated call and a picture message. Reminders will be delivered once a week, at a time chosen by the patient. Patients will be followed up for 24 months or till the primary outcome i.e. virological failure, is reached, whichever is earlier. Self-reported adherence is a secondary outcome. Analysis is by intention-to-treat. A cost-effectiveness study of the intervention will also be carried out.

    Stepping up telecommunications technology in resource-limited healthcare settings is a priority of the World Health Organization. The trial will evaluate if the use of mobile phone reminders can influence adherence to first-line antiretrovirals in an Indian context.

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  • 13.
    Deramore Denver, Belinda
    et al.
    Australian Catholic University, Australia.
    Adolfsson, Margareta
    Jönköping University, School of Education and Communication, HLK, CHILD.
    Froude, Elspeth
    Australian Catholic University, Australia.
    Rosenbaum, Peter
    McMaster University, Canada.
    Imms, Christine
    Australian Catholic University, Australia.
    Methods for conceptualising ‘visual ability’ as a measurable construct in children with cerebral palsy2017In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 17, no 46Article in journal (Refereed)
    Abstract [en]

    Background: Vision influences functioning and disability of children with cerebral palsy, so there is a growing need for psychometrically robust tools to advance assessment of children’s vision abilities in clinical practice and research. Vision is a complex construct, and in the absence of clarity about this construct it is challenging to know whether valid, reliable measures exist. This study reports a method for conceptualising ‘visual ability’ as a measurable construct. Methods: Using the items from 19 assessment tools previously identified in a systematic review, this study used a two-phase process: first, deductive content analysis linked items to the International Classification of Functioning, Disability and Health - Child and Youth version (ICF-CY), and second, vision-specific ‘Activity’-level items were explored using inductive thematic analysis. Results: The linking and content analysis identified that existing assessment tools are measuring vision across the ICF-CY domains of Body Functions, Activities and Participation, and Environmental and Personal Factors. Items specifically coded to vision at the Activity level were defined as measuring ‘how vision is used’, and these items form the basis of the conceptualisation that ‘visual ability’ is measurable as a single construct. The thematic analysis led to the identification of 3 categories containing 13 themes that reflect a child’s observable visual behaviours. Seven abilities reflect how a child uses vision: responds or reacts, initiates, maintains or sustains looking, changes or shifts looking, searches, locates or finds, and follows. Four interactions reflect the contexts in which a child uses their vision to purposefully interact: watches and visually interacts with people and faces, objects, over distance, and with hands. Finally, two themes reflect a child’s overall use of vision in daily activities: frequency of use, and efficiency of use. Conclusions: This study demonstrates an approach to exploring and explaining a complex topic utilising World Health Organization language and building on existing research. Despite the complexity of vision, the concept of ‘how vision is used’ can be clearly defined as a measurable construct at the Activity level of the ICF-CY. This study has identified observable visual behaviours that may be developed into items assessing how vision is used in daily activities.

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    Additional File 1: Study-Specific Guidelines: ICF-CY Linking Rules & Challenges
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    Additional File 2: Results tables for Body Function and Environmental factor codes
  • 14.
    Ekberg, Joakim
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Social Medicine and Public Health Science.
    Timpka, Toomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medical and Health Sciences, Social Medicine and Public Health Science.
    Bång, Magnus
    Linköping University, Department of Computer and Information Science, MDALAB - Human Computer Interfaces. Linköping University, The Institute of Technology.
    Fröberg, Anders
    Linköping University, Department of Computer and Information Science, MDALAB - Human Computer Interfaces. Linköping University, The Institute of Technology.
    Halje, Karin
    Unga vuxna Clinic .
    Eriksson, Henrik
    Linköping University, Department of Computer and Information Science, MDALAB - Human Computer Interfaces. Linköping University, The Institute of Technology.
    Cell phone-supported cognitive behavioural therapy for anxiety disorders: a protocol for effectiveness studies in frontline settings.2011In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 11, p. 3-Article in journal (Refereed)
    Abstract [en]

    The resulting protocol (NCT01205191 at clinicaltrials.gov) for use in frontline clinical practice in which effectiveness, adherence, and the role of the therapists are analyzed, provides evidence for what are truly valuable cell phone-supported CBT treatments and guidance for the broader introduction of CBT in health services.

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    FULLTEXT01
  • 15.
    Ekstrand, Joakim
    et al.
    Kristianstad University, Sweden.
    Westergren, Albert
    Kristianstad University, Sweden.
    Årestedt, Kristofer
    Linnaeus University, Faculty of Health and Life Sciences, Department of Health and Caring Sciences. Linnaeus University, Linnaeus Knowledge Environments, Sustainable Health. Region Kalmar County, Sweden.
    Hellström, Amanda
    Linnaeus University, Faculty of Health and Life Sciences, Department of Health and Caring Sciences.
    Hagell, Peter
    Kristianstad University, Sweden.
    Transformation of Rasch model logits for enhanced interpretability2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, no 1, article id 332Article in journal (Refereed)
    Abstract [en]

    Background: The Rasch model allows for linear measurement based on ordinal item responses from rating scales commonly used to assess health outcomes. Such linear measures may be inconvenient since they are expressed as log-odds units (logits) that differ from scores that users may be familiar with. It can therefore be desirable to transform logits into more user-friendly ranges that preserve their linear properties. In addition to user-defined ranges, three general transformations have been described in the literature: the least measurable difference (LMD), the standard error of measurement (SEM) and the least significant difference (LSD). The LMD represents the smallest possible meaningful unit, SEM relates the transformed scale values to measurement uncertainty (one unit on the transformed scale represents roughly one standard error), and LSD represents a lower bound for how coarse the transformed scale can be without loss of valid information. However, while logit transformations are relatively common in the health sciences, use of LMD, SEM and LSD transformations appear to be uncommon despite their potential role. Methods: Logit transformations were empirically illustrated based on 1053 responses to the Epworth Sleepiness Scale. Logit measures were transformed according to the LMD, SEM and LSD, and into 0-10, 0-100, and the original raw score (0-24) ranges. These transformations were conducted using a freely available Excel tool, developed by the authors, that transforms logits into user-defined ranges along with the LMD, SEM and LSD transformations. Results: Resulting LMD, SEM and LSD transformations ranged 0-34, 0-17 and 0-12, respectively. When considering these relative to the three user-defined ranges, it is seen that the 0-10 range is narrower than the LSD range (i.e., loss of valid information), and a 0-100 range gives the impression of better precision than there is, since it is considerably wider than the LMD range. However, the 0-24 transformation appears reasonable since it is wider than the LSD, but narrower than the LMD ranges. Conclusions: It is suggested that LMD, SEM and LSD transformations are valuable for benchmarking in deciding appropriate ranges when transforming logit measures. This process can be aided by the Excel tool presented and illustrated in this paper.

  • 16.
    Flynn, Terry N
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Centre for Research Ethics and Bioethics.
    Louviere, Jordan J
    Peters, Tim J
    Coast, Joanna
    Estimating preferences for a dermatology consultation using Best-Worst Scaling: comparison of various methods of analysis.2008In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 8, p. 76-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Additional insights into patient preferences can be gained by supplementing discrete choice experiments with best-worst choice tasks. However, there are no empirical studies illustrating the relative advantages of the various methods of analysis within a random utility framework.

    METHODS: Multinomial and weighted least squares regression models were estimated for a discrete choice experiment. The discrete choice experiment incorporated a best-worst study and was conducted in a UK NHS dermatology context. Waiting time, expertise of doctor, convenience of attending and perceived thoroughness of care were varied across 16 hypothetical appointments. Sample level preferences were estimated for all models and differences between patient subgroups were investigated using covariate-adjusted multinomial logistic regression.

    RESULTS: A high level of agreement was observed between results from the paired model (which is theoretically consistent with the 'maxdiff' choice model) and the marginal model (which is only an approximation to it). Adjusting for covariates showed that patients who felt particularly affected by their skin condition during the previous week displayed extreme preference for short/no waiting time and were less concerned about other aspects of the appointment. Higher levels of educational attainment were associated with larger differences in utility between the levels of all attributes, although the attributes per se had the same impact upon choices as those with lower levels of attainment. The study also demonstrated the high levels of agreement between summary analyses using weighted least squares and estimates from multinomial models.

    CONCLUSION: Robust policy-relevant information on preferences can be obtained from discrete choice experiments incorporating best-worst questions with relatively small sample sizes. The separation of the effects due to attribute impact from the position of levels on the latent utility scale is not possible using traditional discrete choice experiments. This separation is important because health policies to change the levels of attributes in health care may be very different from those aiming to change the attribute impact per se. The good approximation of summary analyses to the multinomial model is a useful finding, because weighted least squares choice totals give better insights into the choice model and promote greater familiarity with the preference data.

  • 17.
    Fottrell, Edward
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Byass, Peter
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Berhane, Yemane
    Addis Continental Inst Publ Hlth, Addis Ababa, Ethiopia.
    Demonstrating the robustness of population surveillance data: implications of error rates on demographic and mortality estimates2008In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 8, p. Article nr 13-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: As in any measurement process, a certain amount of error may be expected in routine population surveillance operations such as those in demographic surveillance sites (DSSs). Vital events are likely to be missed and errors made no matter what method of data capture is used or what quality control procedures are in place. The extent to which random errors in large, longitudinal datasets affect overall health and demographic profiles has important implications for the role of DSSs as platforms for public health research and clinical trials. Such knowledge is also of particular importance if the outputs of DSSs are to be extrapolated and aggregated with realistic margins of error and validity.

    METHODS: This study uses the first 10-year dataset from the Butajira Rural Health Project (BRHP) DSS, Ethiopia, covering approximately 336,000 person-years of data. Simple programmes were written to introduce random errors and omissions into new versions of the definitive 10-year Butajira dataset. Key parameters of sex, age, death, literacy and roof material (an indicator of poverty) were selected for the introduction of errors based on their obvious importance in demographic and health surveillance and their established significant associations with mortality. Defining the original 10-year dataset as the 'gold standard' for the purposes of this investigation, population, age and sex compositions and Poisson regression models of mortality rate ratios were compared between each of the intentionally erroneous datasets and the original 'gold standard' 10-year data.

    RESULTS: The composition of the Butajira population was well represented despite introducing random errors, and differences between population pyramids based on the derived datasets were subtle. Regression analyses of well-established mortality risk factors were largely unaffected even by relatively high levels of random errors in the data.

    CONCLUSION: The low sensitivity of parameter estimates and regression analyses to significant amounts of randomly introduced errors indicates a high level of robustness of the dataset. This apparent inertia of population parameter estimates to simulated errors is largely due to the size of the dataset. Tolerable margins of random error in DSS data may exceed 20%. While this is not an argument in favour of poor quality data, reducing the time and valuable resources spent on detecting and correcting random errors in routine DSS operations may be justifiable as the returns from such procedures diminish with increasing overall accuracy. The money and effort currently spent on endlessly correcting DSS datasets would perhaps be better spent on increasing the surveillance population size and geographic spread of DSSs and analysing and disseminating research findings.

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    Demonstrating the robustness of population surveillance data: implications of error rates on demographic and mortality estimates
  • 18.
    Hagquist, Curt
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Centre for Research on Child and Adolescent Mental Health (from 2013).
    Explaining differential item functioning focusing on the crucial role of external information: An example from the measurement of adolescent mental health2019In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 19, no 1, article id 1985Article in journal (Refereed)
    Abstract [en]

    Background: An overarching objective in research comparing different sample groups is to ensure that the reported differences in outcomes are not affected by differences between groups in the functioning of the measurement instruments, i.e. the items have to work in the same way for the different sample groups to be compared. Lack of invariance across sample groups are commonly called Differential Item Functioning (DIF). There is a sense in which the DIF of an item can be taken account of by resolving (splitting) the item into group specific items, rather than deleting the item. Resolving improves fit, retains the reliability and content provided by the item, and compensates for the DIF in estimation of person parameters on the scale of the instrument. However, it destroys invariance of the item’s parameter value among the groups. Whether or not a DIF item should be resolved depends on whether the source of the DIF is relevant or irrelevant for the content of the variable. The present paper shows how external information can be used to investigate if the gender DIF found in the item “Stomach ache” in a psychosomatic symptoms scale used among adolescents may reflect abdominal pain because of a biological factor, the girls’ menstrual periods. Methods: Swedish data from the international Health Behaviour in School-aged Children study (HBSC) collected in 2005/06, 2009/10 and 2013/14 were used, comprising a total of 18,983 students in grades 5, 7 and 9. A composite measure of eight items of psychosomatic problems was analysed for DIF with respect to gender and menstrual periods using the Rasch model. Results: The results support the hypothesis that the source of the gender DIF for the item “Stomach ache” is a gender specific biological factor. In that case the DIF should be resolved if the psychosomatic measure is not intended to tap information about abdominal pain caused by a gender specific biological factor. In contrast, if the measure is intended to tap such information, the DIF should not be resolved. Conclusions: The conceptualisation of the measure governs whether the item showing DIF should be resolved or not. Keywords: Differential item functioning (DIF), Resolving for DIF, Psychosomatic problems, Rasch model, Source of DIF, Validity and reliability, HBSC

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  • 19.
    Hammarström, Anne
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Socialmedicin.
    Westerlund, Hugo
    Kirves, Kaisa
    Nygren, Karina
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Socialmedicin.
    Virtanen, Pekka
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Socialmedicin. School of Health Sciences, University of Tampere, Tampere, Finland.
    Hägglöf, Bruno
    Umeå University, Faculty of Medicine, Department of Clinical Sciences, Child and Adolescent Psychiatry.
    Addressing challenges of validity and internal consistency of mental health measures in a 27- year longitudinal cohort study–the Northern Swedish Cohort study2016In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 16, article id 4Article in journal (Refereed)
    Abstract [en]

    Background:There are inherent methodological challenges in the measurement of mental health problems in longitudinal research. There is constant development in definitions, taxonomies and demands concerning the properties of mental health measurements. The aim of this paper was to construct composite measures of mental health problems (according to today’s standard) from single questionnaire items devised in the early 1980s, and to evaluate their internal consistency and factorial invariance across the life course using the Northern Swedish Cohort.Methods:All pupils in the last year of compulsory school in Luleå in 1981 (n= 1083) form a prospective cohort study where the participants have been followed with questionnaires from the age of 16 (in 1981) until the age of43 (in 2008). We created and tested the following composite measures from self-reports at each follow-up:depressive symptoms, anxiety symptoms, functional somatic symptoms, modified GHQ and positive health. Validity and internal consistency were tested by confirmatory factor analysis, including tests of factorial invariance over time.Results:As an overall assessment, the results showed that the composite measures (based on more than 30-year-old single item questions) are likely to have acceptable factorial invariance as well as internal consistency over time.Conclusions:Testing the properties of the mental health measures used in older studies according to the standards of today is of great importance in longitudinal research. Our study demonstrates that composite measures of mental health problems can be constructed from single items which are more than 30 years old and that these measures seem to have the same factorial structure and internal consistency across a significant part of the life course. Thus, it can be possible to overcome some specific inherent methodological challenges in using historical data in longitudinal research.

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  • 20.
    Hammarström, Anne
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Public Health. Umeå universitet, Socialmedicin.
    Westerlund, Hugo
    Kirves, Kaisa
    Nygren, Karina
    Umeå universitet, Socialmedicin.
    Virtanen, Pekka
    Umeå universitet, Socialmedicin.
    Hägglöf, Bruno
    Umeå universitet, Barn- och ungdomspsykiatri.
    Addressing challenges of validity and internal consistency of mental health measures in a 27- year longitudinal cohort study–the Northern Swedish Cohort study2016In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 16, article id 4Article in journal (Refereed)
    Abstract [en]

    Background:There are inherent methodological challenges in the measurement of mental health problems in longitudinal research. There is constant development in definitions, taxonomies and demands concerning the properties of mental health measurements. The aim of this paper was to construct composite measures of mental health problems (according to today’s standard) from single questionnaire items devised in the early 1980s, and to evaluate their internal consistency and factorial invariance across the life course using the Northern Swedish Cohort.Methods:All pupils in the last year of compulsory school in Luleå in 1981 (n= 1083) form a prospective cohort study where the participants have been followed with questionnaires from the age of 16 (in 1981) until the age of43 (in 2008). We created and tested the following composite measures from self-reports at each follow-up:depressive symptoms, anxiety symptoms, functional somatic symptoms, modified GHQ and positive health. Validity and internal consistency were tested by confirmatory factor analysis, including tests of factorial invariance over time.Results:As an overall assessment, the results showed that the composite measures (based on more than 30-year-old single item questions) are likely to have acceptable factorial invariance as well as internal consistency over time.Conclusions:Testing the properties of the mental health measures used in older studies according to the standards of today is of great importance in longitudinal research. Our study demonstrates that composite measures of mental health problems can be constructed from single items which are more than 30 years old and that these measures seem to have the same factorial structure and internal consistency across a significant part of the life course. Thus, it can be possible to overcome some specific inherent methodological challenges in using historical data in longitudinal research.

  • 21. Hammarström, Anne
    et al.
    Westerlund, Hugo
    Stockholm University, Faculty of Social Sciences, Stress Research Institute.
    Kirves, Kaisa
    Nygren, Karina
    Virtanen, Pekka
    Hägglöf, Bruno
    Addressing challenges of validity and internal consistency of mental health measures in a 27-year longitudinal cohort study - the Northern Swedish Cohort study2016In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 16, no 1, article id 4Article in journal (Refereed)
    Abstract [en]

    Background: There are inherent methodological challenges in the measurement of mental health problems in longitudinal research. There is constant development in definitions, taxonomies and demands concerning the properties of mental health measurements. The aim of this paper was to construct composite measures of mental health problems (according to today's standard) from single questionnaire items devised in the early 1980s, and to evaluate their internal consistency and factorial invariance across the life course using the Northern Swedish Cohort. Methods: All pupils in the last year of compulsory school in Lulea in 1981 (n = 1083) form a prospective cohort study where the participants have been followed with questionnaires from the age of 16 (in 1981) until the age of 43 (in 2008). We created and tested the following composite measures from self-reports at each follow-up: depressive symptoms, anxiety symptoms, functional somatic symptoms, modified GHQ and positive health. Validity and internal consistency were tested by confirmatory factor analysis, including tests of factorial invariance over time. Results: As an overall assessment, the results showed that the composite measures (based on more than 30-year-old single item questions) are likely to have acceptable factorial invariance as well as internal consistency over time. Conclusions: Testing the properties of the mental health measures used in older studies according to the standards of today is of great importance in longitudinal research. Our study demonstrates that composite measures of mental health problems can be constructed from single items which are more than 30 years old and that these measures seem to have the same factorial structure and internal consistency across a significant part of the life course. Thus, it can be possible to overcome some specific inherent methodological challenges in using historical data in longitudinal research.

  • 22.
    Harder, Thomas
    et al.
    Robert Koch Institute, Berlin, Germany.
    Takla, Anja
    Robert Koch Institute, Berlin, Germany.
    Rehfuess, Eva
    University of Munich, Germany .
    Sanchez-Vivar, Alex
    Health Protection Scotland (HPS); Scottish Health Protection Network (HPN), Glasgow, UK.
    Matysiak-Klose, Dorothea
    Robert Koch Institute, Berlin, Germany.
    Eckmanns, Tim
    Robert Koch Institute, Berlin, Germany.
    Krause, Gerard
    Robert Koch Institute, Berlin, Germany.
    de Carvalho Gomes, Helena
    European Centre for Disease Prevention and Control ECDC, Stockhom, Sweden.
    Jansen, Andreas
    European Centre Disease for Prevention and Control ECDC, Stockhom, Sweden.
    Ellis, Simon
    National Institute Health and Care Excellence NICE, London, UK.
    Forland, Frode
    Royal Tropical Institute, Amsterdam, The Netherlands; Norwegian Institute of Public Heatlh, Oslo, Norway.
    James, Roberta
    Scottish Intercollegiate Guidelines Network (SIGN), Edinburgh, UK.
    Meerpohl, Joerg J.
    University Medical Center Freiburg, Germany .
    Morgan, Antony
    National Institute for Health and Care Excellence (NICE), London, UK.
    Schuenemann, Holger
    McMaster University Health Sciences Centre, Hamilton, ON, Canada.
    Zuiderent-Jerak, Teun
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Wichmann, Ole
    Robert Koch Institute, Berlin, Germany .
    Evidence-based decision-making in infectious diseases epidemiology, prevention and control: matching research questions to study designs and quality appraisal tools2014In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 14, no 69Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    The Project on a Framework for Rating Evidence in Public Health (PRECEPT) was initiated and is being funded by the European Centre for Disease Prevention and Control (ECDC) to define a methodology for evaluating and grading evidence and strength of recommendations in the field of public health, with emphasis on infectious disease epidemiology, prevention and control. One of the first steps was to review existing quality appraisal tools (QATs) for individual research studies of various designs relevant to this area, using a question-based approach.

    METHODS:

    Through team discussions and expert consultations, we identified 20 relevant types of public health questions, which were grouped into six domains, i.e. characteristics of the pathogen, burden of disease, diagnosis, risk factors, intervention, and implementation of intervention. Previously published systematic reviews were used and supplemented by expert consultation to identify suitable QATs. Finally, a matrix was constructed for matching questions to study designs suitable to address them and respective QATs. Key features of each of the included QATs were then analyzed, in particular in respect to its intended use, types of questions and answers, presence/absence of a quality score, and if a validation was performed.

    RESULTS:

    In total we identified 21 QATs and 26 study designs, and matched them. Four QATs were suitable for experimental quantitative study designs, eleven for observational quantitative studies, two for qualitative studies, three for economic studies, one for diagnostic test accuracy studies, and one for animal studies. Included QATs consisted of six to 28 items. Six of the QATs had a summary quality score. Fourteen QATs had undergone at least one validation procedure.

    CONCLUSIONS:

    The results of this methodological study can be used as an inventory of potentially relevant questions, appropriate study designs and QATs for researchers and authorities engaged with evidence-based decision-making in infectious disease epidemiology, prevention and control.

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  • 23.
    Hasson, H.
    et al.
    Karolinska Institutet, Stockholm, .
    Leviton, L.
    Robert Wood Johnson Foundation, Princeton, United States.
    von Thiele Schwarz, Ulrica
    Mälardalen University, School of Health, Care and Social Welfare, Health and Welfare.
    A typology of useful evidence: Approaches to increase the practical value of intervention research2020In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 20, no 1, article id 255Article in journal (Refereed)
    Abstract [en]

    Background: Too often, studies of evidence-based interventions (EBIs) in preventive, community, and health care are not sufficiently useful to end users (typically practitioners, patients, policymakers, or other researchers). The ways in which intervention studies are conventionally conducted and reported mean that there is often a shortage of information when an EBI is used in practice. The paper aims to invite the research community to consider ways to optimize not only the trustworthiness but also the research's usefulness in intervention studies. This is done by proposing a typology that provides some approaches to useful EBIs for intervention researchers. The approaches originate from different research fields and are summarized to highlight their potential benefits from a usefulness perspective. Main message: The typology consists of research approaches to increase the usefulness of EBIs by improving the reporting of four features in intervention studies: (1) the interventions themselves, including core components and appropriate adaptations; (2) strategies to support-high-quality implementation of the interventions; (3) generalizations about the evidence in a variety of contexts; and (4) outcomes based on end users' preferences and knowledge. The research approaches fall into three levels: Description, Analysis, and Design. The first level, Description, outlines what types of information about the intervention and its implementation, context, and outcomes can be helpful for end users. Research approaches under analysis offers alternative ways of analyzing data, increasing the precision of information provided to end users. Approaches summarized under design involve more radical changes and far-reaching implications for how research can provide more useful information. These approaches partly flip the order of efficacy and effectiveness, focusing not on whether an intervention works in highly controlled and optimal circumstances, but first and foremost whether an intervention can be implemented and lead to anticipated outcomes in everyday practice. Conclusions: The research community, as well as the end users of research, are invited to consider ways to optimize research's usefulness as well as its trustworthiness. Many of the research approaches in the typology are not new, and their contributions to quality have been described for generations - but their contributions to useful knowledge need more attention. 

  • 24.
    Hausken-Sutter, S E
    et al.
    Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden.
    Boije Af Gennäs, K
    Department of Sport Science, Malmö University, Malmö, Sweden.
    Schubring, A
    Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden; Institute of Sociology and Gender Studies, German Sport University Cologne, Cologne, Germany.
    Grau, S
    Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden.
    Jungmalm, J
    Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden.
    Barker-Ruchti, Natalie
    Örebro University, School of Health Sciences. Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden.
    Interdisciplinary sport injury research and the integration of qualitative and quantitative data2023In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 23, no 1, article id 110Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: To understand and prevent sport injuries, scholars have employed different scientific approaches and research methods. Traditionally, this research has been monodisciplinary, relying on one subdiscipline of sport science and applying qualitative or quantitative research methods. Recently, scholars have argued that traditional approaches fail to address contextual components of sport and the nonlinear interactions between different aspects in and around the athlete, and, as a way forward, called for alternative approaches to sport injury research. Discussion of alternative approaches are today taking place, however, practical examples that demonstrate what such approaches entails are rare. Therefore, the purpose of this paper is to draw on an interdisciplinary research approach to (1) outline an interdisciplinary case analysis procedure (ICAP); and (2) provide an example for future interdisciplinary sport injury research.

    METHODS: We adopt an established definition and application of interdisciplinary research to develop and pilot the ICAP for interdisciplinary sport injury teams aiming to integrate qualitative and quantitative sport injury data. The development and piloting of ICAP was possible by drawing on work conducted in the interdisciplinary research project "Injury-free children and adolescents: Towards better practice in Swedish football" (the FIT project).

    RESULTS: The ICAP guides interdisciplinary sport injury teams through three stages: 1. Create a more comprehensive understanding of sport injury aetiology by drawing on existing knowledge from multiple scientific perspectives; 2. Collate analysed qualitative and quantitative sport injury data into a multilevel data catalogue; and 3. Engage in an integrated discussion of the collated data in the interdisciplinary research team.

    CONCLUSION: The ICAP is a practical example of how an interdisciplinary team of sport injury scholars can approach the complex problem of sport injury aetiology and work to integrate qualitative and quantitative data through three stages. The ICAP is a step towards overcoming the obstacles of integrating qualitative and quantitative methods and data that scholars have identified.

  • 25.
    Hausken-Sutter, Solveig E.
    et al.
    Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden.
    Schubring, Astrid
    Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden.
    Grau, Stefan
    Department of Food and Nutrition, and Sport Science, University of Gothenburg, Gothenburg, Sweden.
    Boije af Gennäs, Klara
    Department of Sports Sciences, Malmö University, Malmö, Sweden.
    Barker-Ruchti, Natalie
    Örebro University, School of Health Sciences.
    Methodological implications of adapting and applying a web‑based questionnaire on health problems to adolescent football players2021In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 21, no 252Article in journal (Refereed)
    Abstract [en]

    Background: The Oslo Sport Trauma Research Centre Questionnaire on Health Problems (OSTRC‑H) has become a popular tool to monitor health status in athletes. Originally developed for adult athletes, the tool is today also being used in adolescent athletes. However, little is known on the suitability of the questionnaire for the adolescent age group and the methodological implications of applying the tool to prospectively monitor illness and injury. To address this gap in methodological knowledge, the aim of this study is to outline and discuss the adaption and application process of the OSTRC‑H to adolescent football players.

    Method: The adaption process included a slightly modified back‑translation method to translate the questionnaire. The application process included a web‑based version of the Swedish OSTRC‑H sent out once a week over 23 weeks to 115 adolescent football players aged 10‑19 attending two football schools in Sweden. The response rate and prevalence of health problems over 23 weeks were calculated as feasibility indicators. Additionally, comprehensibility questions were added to the questionnaire in the end of the study.

    Result: No major disagreement was found between the original and translated versions of the questionnaire. However, significant changes to the wording of the questions and answer categories were necessary to adapt it to ado‑lescents. A visual body figure was also added. The average weekly response rate was 38% (SD 13.5). To increase this rate, questionnaire data was gathered retrospectively through telephone and email contact with the participants and their parents, elevating the response rate to 53% (SD 15.5). The adolescents experienced the questionnaire as easy to understand and to cover all relevant health problems.

    Conclusion: Our study demonstrates the importance of adapting the questionnaire to the adolescent target group through translation, pre‑tests, adjustments of wording and the facilitation of answering the questionnaire using a visual body figure. The study further shows the importance of keeping close and personal contact with the participants, their parents, teachers, and coaches throughout data collection. Future studies should take into account the age group and study context when adapting and applying the OSTRC‑H to adolescents.

  • 26.
    Hausken-Sutter, Solveig E.
    et al.
    Univ Gothenburg, Dept Food & Nutr & Sport Sci, Box 300, SE-40530 Gothenburg, Sweden..
    Schubring, Astrid
    Univ Gothenburg, Dept Food & Nutr & Sport Sci, Box 300, SE-40530 Gothenburg, Sweden..
    Grau, Stefan
    Univ Gothenburg, Dept Food & Nutr & Sport Sci, Box 300, SE-40530 Gothenburg, Sweden..
    Boije af Gennäs, Klara
    Malmö University, Faculty of Education and Society (LS), Department of Sport Sciences (IDV).
    Barker-Ruchti, Natalie
    Univ Gothenburg, Dept Food & Nutr & Sport Sci, Box 300, SE-40530 Gothenburg, Sweden.;Orebro Univ, Sch Hlth Sci, Orebro, Sweden..
    Methodological implications of adapting and applying a web-based questionnaire on health problems to adolescent football players2021In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 21, no 1, article id 252Article in journal (Refereed)
    Abstract [en]

    Background The Oslo Sport Trauma Research Centre Questionnaire on Health Problems (OSTRC-H) has become a popular tool to monitor health status in athletes. Originally developed for adult athletes, the tool is today also being used in adolescent athletes. However, little is known on the suitability of the questionnaire for the adolescent age group and the methodological implications of applying the tool to prospectively monitor illness and injury. To address this gap in methodological knowledge, the aim of this study is to outline and discuss the adaption and application process of the OSTRC-H to adolescent football players. Method The adaption process included a slightly modified back-translation method to translate the questionnaire. The application process included a web-based version of the Swedish OSTRC-H sent out once a week over 23 weeks to 115 adolescent football players aged 10-19 attending two football schools in Sweden. The response rate and prevalence of health problems over 23 weeks were calculated as feasibility indicators. Additionally, comprehensibility questions were added to the questionnaire in the end of the study. Result No major disagreement was found between the original and translated versions of the questionnaire. However, significant changes to the wording of the questions and answer categories were necessary to adapt it to adolescents. A visual body figure was also added. The average weekly response rate was 38% (SD 13.5). To increase this rate, questionnaire data was gathered retrospectively through telephone and email contact with the participants and their parents, elevating the response rate to 53% (SD 15.5). The adolescents experienced the questionnaire as easy to understand and to cover all relevant health problems. Conclusion Our study demonstrates the importance of adapting the questionnaire to the adolescent target group through translation, pre-tests, adjustments of wording and the facilitation of answering the questionnaire using a visual body figure. The study further shows the importance of keeping close and personal contact with the participants, their parents, teachers, and coaches throughout data collection. Future studies should take into account the age group and study context when adapting and applying the OSTRC-H to adolescents.

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  • 27.
    Hausken-Sutter, Solveige E
    et al.
    Department of Food and Nutrition, and Sport Science, University of Gothenburg.
    Boije af Gennäs, Klara
    Malmö University, Faculty of Education and Society (LS), Department of Sport Sciences (IDV).
    Schubring, Astrid
    Department of Food and Nutrition, and Sport Science, University of Gothenburg ; Institute of Sociology and Gender Studies, German Sport University Cologne, Cologne, Germany.
    Grau, Stefan
    Department of Food and Nutrition, and Sport Science, University of Gothenburg.
    Jungmalm, Jonatan
    Department of Food and Nutrition, and Sport Science, University of Gothenburg.
    Barker-Ruchti, Natalie
    Department of Food and Nutrition, and Sport Science, University of Gothenburg; School of Health Sciences, Örebro University, Örebro, Sweden.
    Interdisciplinary sport injury research and the integration of qualitative and quantitative data.2023In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 23, no 1, article id 110Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: To understand and prevent sport injuries, scholars have employed different scientific approaches and research methods. Traditionally, this research has been monodisciplinary, relying on one subdiscipline of sport science and applying qualitative or quantitative research methods. Recently, scholars have argued that traditional approaches fail to address contextual components of sport and the nonlinear interactions between different aspects in and around the athlete, and, as a way forward, called for alternative approaches to sport injury research. Discussion of alternative approaches are today taking place, however, practical examples that demonstrate what such approaches entails are rare. Therefore, the purpose of this paper is to draw on an interdisciplinary research approach to (1) outline an interdisciplinary case analysis procedure (ICAP); and (2) provide an example for future interdisciplinary sport injury research.

    METHODS: We adopt an established definition and application of interdisciplinary research to develop and pilot the ICAP for interdisciplinary sport injury teams aiming to integrate qualitative and quantitative sport injury data. The development and piloting of ICAP was possible by drawing on work conducted in the interdisciplinary research project "Injury-free children and adolescents: Towards better practice in Swedish football" (the FIT project).

    RESULTS: The ICAP guides interdisciplinary sport injury teams through three stages: 1. Create a more comprehensive understanding of sport injury aetiology by drawing on existing knowledge from multiple scientific perspectives; 2. Collate analysed qualitative and quantitative sport injury data into a multilevel data catalogue; and 3. Engage in an integrated discussion of the collated data in the interdisciplinary research team.

    CONCLUSION: The ICAP is a practical example of how an interdisciplinary team of sport injury scholars can approach the complex problem of sport injury aetiology and work to integrate qualitative and quantitative data through three stages. The ICAP is a step towards overcoming the obstacles of integrating qualitative and quantitative methods and data that scholars have identified.

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  • 28.
    Ipekci, Aziz Mert
    et al.
    Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
    Buitrago-Garcia, Diana
    Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland; Graduate School of Health Sciences, University of Bern, Bern, Switzerland.
    Meili, Kaspar Walter
    Umeå University, Faculty of Medicine, Department of Epidemiology and Global Health.
    Krauer, Fabienne
    Centre for Ecological and Evolutionary Synthesis (CEES), University of Oslo, Oslo, Norway.
    Prajapati, Nirmala
    École des Hautes Études en Santé Publique (EHESP), Saint Denis, France.
    Thapa, Shabnam
    Institute of Public Health, Jagiellonian University Medical College, Kraków, Poland.
    Wildisen, Lea
    Institute of Primary Health Care (BIHAM), University of Bern, Bern, Switzerland.
    Araujo-Chaveron, Lucia
    École des Hautes Études en Santé Publique (EHESP), Saint Denis, France.
    Baumann, Lukas
    Department of Internal Medicine, Kantonsspital Olten, Olten, Switzerland.
    Shah, Sanam
    École des Hautes Études en Santé Publique (EHESP), Saint Denis, France.
    Whiteley, Tessa
    École des Hautes Études en Santé Publique (EHESP), Saint Denis, France.
    Solís-García, Gonzalo
    Pediatrics Department, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
    Tsotra, Foteini
    School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, United Kingdom.
    Zhelyazkov, Ivan
    School of Health and Related Research (ScHARR), University of Sheffield, Sheffield, United Kingdom.
    Imeri, Hira
    Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
    Low, Nicola
    Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
    Counotte, Michel Jacques
    Institute of Social and Preventive Medicine, University of Bern, Bern, Switzerland.
    Outbreaks of publications about emerging infectious diseases: the case of SARS-CoV-2 and Zika virus2021In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 21, no 1, article id 50Article in journal (Refereed)
    Abstract [en]

    Background: Outbreaks of infectious diseases generate outbreaks of scientific evidence. In 2016 epidemics of Zika virus emerged, and in 2020, a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a pandemic of coronavirus disease 2019 (COVID-19). We compared patterns of scientific publications for the two infections to analyse the evolution of the evidence. Methods: We annotated publications on Zika virus and SARS-CoV-2 that we collected using living evidence databases according to study design. We used descriptive statistics to categorise and compare study designs over time. Results: We found 2286 publications about Zika virus in 2016 and 21,990 about SARS-CoV-2 up to 24 May 2020, of which we analysed a random sample of 5294 (24%). For both infections, there were more epidemiological than laboratory science studies. Amongst epidemiological studies for both infections, case reports, case series and cross-sectional studies emerged first, cohort and case-control studies were published later. Trials were the last to emerge. The number of preprints was much higher for SARS-CoV-2 than for Zika virus. Conclusions: Similarities in the overall pattern of publications might be generalizable, whereas differences are compatible with differences in the characteristics of a disease. Understanding how evidence accumulates during disease outbreaks helps us understand which types of public health questions we can answer and when.

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  • 29. Kabudula, Chodziwadziwa W.
    et al.
    Clark, Benjamin D.
    Gomez-Olive, Francesc Xavier
    Tollman, Stephen
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health. MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; INDEPTH Network, Accra, Ghana .
    Menken, Jane
    Reniers, Georges
    The promise of record linkage for assessing the uptake of health services in resource constrained settings: a pilot study from South Africa2014In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 14, article id 71Article in journal (Refereed)
    Abstract [en]

    Background: Health and Demographic Surveillance Systems (HDSS) have been instrumental in advancing population and health research in low-and middle-income countries where vital registration systems are often weak. However, the utility of HDSS would be enhanced if their databases could be linked with those of local health facilities. We assess the feasibility of record linkage in rural South Africa using data from the Agincourt HDSS and a local health facility. Methods: Using a gold standard dataset of 623 record pairs matched by means of fingerprints, we evaluate twenty record linkage scenarios (involving different identifiers, string comparison techniques and with and without clerical review) based on the Fellegi-Sunter probabilistic record linkage model. Matching rates and quality are measured by their sensitivity and positive predictive value (PPV). Background characteristics of matched and unmatched cases are compared to assess systematic bias in the resulting record-linked dataset. Results: A hybrid approach of deterministic followed by probabilistic record linkage, and scenarios that use an extended set of identifiers including another household member's first name yield the best results. The best fully automated record linkage scenario has a sensitivity of 83.6% and PPV of 95.1%. The sensitivity and PPV increase to 84.3% and 96.9%, respectively, when clerical review is undertaken on 10% of the record pairs. The likelihood of being linked is significantly lower for females, non-South Africans and the elderly. Conclusion: Using records matched by means of fingerprints as the gold standard, we have demonstrated the feasibility of fully automated probabilistic record linkage using identifiers that are routinely collected in health facilities in South Africa. Our study also shows that matching statistics can be improved if other identifiers (e.g., another household member's first name) are added to the set of matching variables, and, to a lesser extent, with clerical review. Matching success is, however, correlated with background characteristics that are indicative of the instability of personal attributes over time (e.g., surname in the case of women) or with misreporting (e.g., age).

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  • 30.
    Kelfve, Susanne
    et al.
    Linköping University, Department of Culture and Society, Division of Social Work. Linköping University, Faculty of Arts and Sciences. Karolinska Inst, Sweden; Stockholm Univ, Sweden.
    Kivi, Marie
    Univ Gothenburg, Sweden.
    Johansson, Boo
    Univ Gothenburg, Sweden.
    Lindwall, Magnus
    Univ Gothenburg, Sweden; Swedish Sch Sport & Hlth Sci GIH, Sweden.
    Going web or staying paper? The use of web-surveys among older people2020In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 20, no 1, article id 252Article in journal (Refereed)
    Abstract [en]

    Background Web-surveys are increasingly used in population studies. Yet, web-surveys targeting older individuals are still uncommon for various reasons. However, with younger cohorts approaching older age, the potentials for web-surveys among older people might be improved. In this study, we investigated response patterns in a web-survey targeting older adults and the potential importance of offering a paper-questionnaire as an alternative to the web-questionnaire. Methods We analyzed data from three waves of a retirement study, in which a web-push methodology was used and a paper questionnaire was offered as an alternative to the web questionnaire in the last reminder. We mapped the response patterns, compared web- and paper respondents and compared different key outcomes resulting from the sample with and without the paper respondents, both at baseline and after two follow-ups. Results Paper-respondents, that is, those that did not answer until they got a paper questionnaire with the last reminder, were more likely to be female, retired, single, and to report a lower level of education, higher levels of depression and lower self-reported health, compared to web-respondents. The association between retirement status and depression was only present among web-respondents. The differences between web and paper respondents were stronger in the longitudinal sample (after two follow-ups) than at baseline. Conclusions We conclude that a web-survey might be a feasible and good alternative in surveys targeting people in the retirement age range. However, without offering a paper-questionnaire, a small but important group will likely be missing with potential biased estimates as the result.

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  • 31.
    Kelfve, Susanne
    et al.
    Stockholm University, Faculty of Social Sciences, Aging Research Center (ARC), (together with KI). Linköping University, Sweden.
    Kivi, Marie
    Johansson, Boo
    Lindwall, Magnus
    Going web or staying paper? The use of web-surveys among older people2020In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 20, no 1, article id 252Article in journal (Refereed)
    Abstract [en]

    Background: Web-surveys are increasingly used in population studies. Yet, web-surveys targeting older individuals are still uncommon for various reasons. However, with younger cohorts approaching older age, the potentials for web-surveys among older people might be improved. In this study, we investigated response patterns in a web-survey targeting older adults and the potential importance of offering a paper-questionnaire as an alternative to the web-questionnaire.

    Methods: We analyzed data from three waves of a retirement study, in which a web-push methodology was used and a paper questionnaire was offered as an alternative to the web questionnaire in the last reminder. We mapped the response patterns, compared web- and paper respondents and compared different key outcomes resulting from the sample with and without the paper respondents, both at baseline and after two follow-ups.

    Results: Paper-respondents, that is, those that did not answer until they got a paper questionnaire with the last reminder, were more likely to be female, retired, single, and to report a lower level of education, higher levels of depression and lower self-reported health, compared to web-respondents. The association between retirement status and depression was only present among web-respondents. The differences between web and paper respondents were stronger in the longitudinal sample (after two follow-ups) than at baseline.

    Conclusions: We conclude that a web-survey might be a feasible and good alternative in surveys targeting people in the retirement age range. However, without offering a paper-questionnaire, a small but important group will likely be missing with potential biased estimates as the result.

  • 32.
    Kelfve, Susanne
    et al.
    Linköping University, Sweden.
    Kivi, Marie
    University of Gothenburg, Sweden.
    Johansson, Boo
    University of Gothenburg, Sweden.
    Lindwall, Magnus
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health. University of Gothenburg, Sweden.
    Going web or staying paper? The use of web-surveys among older people.2020In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 20, no 1, article id 252Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Web-surveys are increasingly used in population studies. Yet, web-surveys targeting older individuals are still uncommon for various reasons. However, with younger cohorts approaching older age, the potentials for web-surveys among older people might be improved. In this study, we investigated response patterns in a web-survey targeting older adults and the potential importance of offering a paper-questionnaire as an alternative to the web-questionnaire.

    METHODS: We analyzed data from three waves of a retirement study, in which a web-push methodology was used and a paper questionnaire was offered as an alternative to the web questionnaire in the last reminder. We mapped the response patterns, compared web- and paper respondents and compared different key outcomes resulting from the sample with and without the paper respondents, both at baseline and after two follow-ups.

    RESULTS: Paper-respondents, that is, those that did not answer until they got a paper questionnaire with the last reminder, were more likely to be female, retired, single, and to report a lower level of education, higher levels of depression and lower self-reported health, compared to web-respondents. The association between retirement status and depression was only present among web-respondents. The differences between web and paper respondents were stronger in the longitudinal sample (after two follow-ups) than at baseline.

    CONCLUSIONS: We conclude that a web-survey might be a feasible and good alternative in surveys targeting people in the retirement age range. However, without offering a paper-questionnaire, a small but important group will likely be missing with potential biased estimates as the result.

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  • 33.
    Ledberg, Anders
    et al.
    Stockholm University, Faculty of Social Sciences, Centre for Social Research on Alcohol and Drugs (SoRAD).
    Wennberg, Peter
    Stockholm University, Faculty of Social Sciences, Centre for Social Research on Alcohol and Drugs (SoRAD).
    Estimating the size of hidden populations from register data2014In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 14, p. 58-Article in journal (Refereed)
    Abstract [en]

    Background: Prevalence estimates of drug use, or of its consequences, are considered important in many contexts and may have substantial influence over public policy. However, it is rarely possible to simply count the relevant individuals, in particular when the defining characteristics might be illegal, as in the drug use case. Consequently methods are needed to estimate the size of such partly 'hidden' populations, and many such methods have been developed and used within epidemiology including studies of alcohol and drug use. Here we introduce a method appropriate for estimating the size of human populations given a single source of data, for example entries in a health-care registry. Methods: The setup is the following: during a fixed time-period, e. g. a year, individuals belonging to the target population have a non-zero probability of being registered. Each individual might be registered multiple times and the time-points of the registrations are recorded. Assuming that the population is closed and that the probability of being registered at least once is constant, we derive a family of maximum likelihood (ML) estimators of total population size. We study the ML estimator using Monte Carlo simulations and delimit the range of cases where it is useful. In particular we investigate the effect of making the population heterogeneous with respect to probability of being registered. Results: The new estimator is asymptotically unbiased and we show that high precision estimates can be obtained for samples covering as little as 25% of the total population size. However, if the total population size is small (say in the order of 500) a larger fraction needs to be sampled to achieve reliable estimates. Further we show that the estimator give reliable estimates even when individuals differ in the probability of being registered. We also compare the ML estimator to an estimator known as Chao's estimator and show that the latter can have a substantial bias when applied to epidemiological data. Conclusions: The population size estimator suggested herein complements existing methods and is less sensitive to certain types of dependencies typical in epidemiological data.

  • 34. Leissner, Philip
    et al.
    Held, Claes
    Rondung, Elisabet
    Mid Sweden University, Faculty of Human Sciences, Department of Psychology and Social Work.
    Olsson, Erik M. G.
    The factor structure of the cardiac anxiety questionnaire, and validation in a post-MI population2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, no 1, article id 338Article in journal (Refereed)
    Abstract [en]

    Background: CVD-patients with higher levels of cardiac anxiety suffer psychologically, as well as being at increased risk for cardiac morbidity and mortality. Therefore it is important to be able to assess CA in a clinical setting. It is currently measured with the Cardiac Anxiety Questionnaire, which has conflicting findings regarding its factor structure, and it has not been validated in a Swedish population. This study aimed to examine the factor structure of CAQ and its psychometric properties in a Swedish CVD-population. Methods: Nine hundred thirty patients post-MI were recruited at different Swedish hospitals and completed the CAQ, along with several other questionnaires. Exploratory factor analysis and confirmatory factor analysis were conducted to explore factor structure and to inspect various factor solutions from previous research. Standard psychometric tests were performed for the CAQ to test its validity and reliability. Results: The exploratory analysis found a model with the factors Fear/Worry, Avoidance and Attention. The confirmatory factor analysis indicated that a 3-factor solution best fitted the data, but with certain items removed. Additionally, psychometric properties turned out acceptable in a Swedish post-MI population. Conclusions: We conclude that the original 3-factor structure of the CAQ is valid, but that the questionnaire could be revised in regard to some items. A shorter 10-items version could also be considered. We also confirm that the CAQ is a valid instrument to measure CA in a Swedish MI-population. Trial registration: The study was registered on ClinicalTrials.gov on 05/01/2012 (NCT01504191). 

  • 35.
    Leissner, Philip
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Healthcare Sciences and e-Health.
    Held, Claes
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Disciplinary Domain of Medicine and Pharmacy, research centers etc., Uppsala Clinical Research Center (UCR). Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Cardiology. Uppsala University Hospital, Uppsala, Sweden.
    Rondung, Elisabet
    Mid Sweden University, Östersund, Sweden.
    Olsson, Erik M.G.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, Healthcare Sciences and e-Health.
    The factor structure of the cardiac anxiety questionnaire, and validation in a post-MI population2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, article id 338Article in journal (Refereed)
    Abstract [en]

    Background: CVD-patients with higher levels of cardiac anxiety suffer psychologically, as well as being at increased risk for cardiac morbidity and mortality. Therefore it is important to be able to assess CA in a clinical setting. It is currently measured with the Cardiac Anxiety Questionnaire, which has conflicting findings regarding its factor structure, and it has not been validated in a Swedish population. This study aimed to examine the factor structure of CAQ and its psychometric properties in a Swedish CVD-population.

    Methods: Nine hundred thirty patients post-MI were recruited at different Swedish hospitals and completed the CAQ, along with several other questionnaires. Exploratory factor analysis and confirmatory factor analysis were conducted to explore factor structure and to inspect various factor solutions from previous research. Standard psychometric tests were performed for the CAQ to test its validity and reliability.

    Results: The exploratory analysis found a model with the factors Fear/Worry, Avoidance and Attention. The confirmatory factor analysis indicated that a 3-factor solution best fitted the data, but with certain items removed. Additionally, psychometric properties turned out acceptable in a Swedish post-MI population.

    Conclusions: We conclude that the original 3-factor structure of the CAQ is valid, but that the questionnaire could be revised in regard to some items. A shorter 10-items version could also be considered. We also confirm that the CAQ is a valid instrument to measure CA in a Swedish MI-population.

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  • 36.
    Lindner, Philip
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Psychology, Clinical psychology. Karolinska Institutet, Sweden; Stockholm County Council, Sweden.
    Johansson, Magnus
    Gajecki, Mikael
    Berman, Anne H.
    Using alcohol consumption diary data from an internet intervention for outcome and predictive modeling: a validation and machine learning study2020In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 20, no 1, article id 111Article in journal (Refereed)
    Abstract [en]

    Background: Alcohol use disorder (AUD) is highly prevalent and presents a large treatment gap. Self-help internet interventions are an attractive approach to lowering thresholds for seeking help and disseminating evidence-based programs at scale. Internet interventions for AUD however suffer from high attrition and since continuous outcome measurements are uncommon, little is known about trajectories and processes. The current study investigates whether data from a non-mandatory alcohol consumption diary, common in internet interventions for AUD, approximates drinks reported at follow-up, and whether data from the first half of the intervention predict treatment success.

    Methods: N = 607 participants enrolled in a trial of online self-help for AUD, made an entry in the non-mandatory consumption diary (total of 9117 entries), and completed the follow-up assessment. Using multiple regression and a subset of calendar data overlapping with the follow-up, scaling factors were derived to account for missing entries per participant and week. Generalized estimating equations with an inverse time predictor were then used to calculate point-estimates of drinks per week at follow-up, the confidence intervals of which were compared to that from the measurement at follow-up. Next, calendar data form the first half of the intervention were retained and summary functions used to create 18 predictors for random forest machine learning models, the classification accuracies of which were ultimately estimated using nested cross-validation.

    Results: While the raw calendar data substantially underestimated drinks reported at follow-up, the confidence interval of the trajectory-derived point-estimate from the adjusted data overlapped with the confidence interval of drinks reported at follow-up. Machine learning models achieved prediction accuracies of 64% (predicting non-hazardous drinking) and 48% (predicting AUD severity decrease), in both cases with higher sensitivity than specificity.

    Conclusions: Data from a non-mandatory alcohol consumption diary, adjusted for missing entries, approximates follow-up data at a group level, suggesting that such data can be used to reveal trajectories and processes during treatment and possibly be used to impute missing follow-up data. At an individual level, however, calendar data from the first half of the intervention did not have high predictive accuracy, presumable due to a high rate of missing data and unclear missing mechanisms.

  • 37.
    Lindner, Philip
    et al.
    Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, Stockholm, Sweden.;Stockholm Cty Council, Stockholm Hlth Care Serv, Stockholm, Sweden.;Stockholm Cty Council, Ctr Dependency Disorders, Stockholm Hlth Care Serv, Stockholm, Sweden.;Stockholm Univ, Dept Psychol, Stockholm, Sweden..
    Johansson, Magnus
    Stockholm Cty Council, Ctr Dependency Disorders, Stockholm Hlth Care Serv, Stockholm, Sweden.;Karolinska Inst, Dept Publ Hlth, Stockholm, Sweden..
    Gajecki, Mikael
    Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, Stockholm, Sweden.;Stockholm Cty Council, Stockholm Hlth Care Serv, Stockholm, Sweden.;Stockholm Cty Council, Ctr Dependency Disorders, Stockholm Hlth Care Serv, Stockholm, Sweden..
    Berman, Anne H.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology. Karolinska Inst, Dept Clin Neurosci, Ctr Psychiat Res, Stockholm, Sweden.;Stockholm Cty Council, Ctr Dependency Disorders, Stockholm Hlth Care Serv, Stockholm, Sweden..
    Using alcohol consumption diary data from an internet intervention for outcome and predictive modeling: a validation and machine learning study2020In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 20, article id 111Article in journal (Refereed)
    Abstract [en]

    Background: Alcohol use disorder (AUD) is highly prevalent and presents a large treatment gap. Self-help internet interventions are an attractive approach to lowering thresholds for seeking help and disseminating evidence-based programs at scale. Internet interventions for AUD however suffer from high attrition and since continuous outcome measurements are uncommon, little is known about trajectories and processes. The current study investigates whether data from a non-mandatory alcohol consumption diary, common in internet interventions for AUD, approximates drinks reported at follow-up, and whether data from the first half of the intervention predict treatment success.

    Methods: N = 607 participants enrolled in a trial of online self-help for AUD, made an entry in the non-mandatory consumption diary (total of 9117 entries), and completed the follow-up assessment. Using multiple regression and a subset of calendar data overlapping with the follow-up, scaling factors were derived to account for missing entries per participant and week. Generalized estimating equations with an inverse time predictor were then used to calculate point-estimates of drinks per week at follow-up, the confidence intervals of which were compared to that from the measurement at follow-up. Next, calendar data form the first half of the intervention were retained and summary functions used to create 18 predictors for random forest machine learning models, the classification accuracies of which were ultimately estimated using nested cross-validation.

    Results: While the raw calendar data substantially underestimated drinks reported at follow-up, the confidence interval of the trajectory-derived point-estimate from the adjusted data overlapped with the confidence interval of drinks reported at follow-up. Machine learning models achieved prediction accuracies of 64% (predicting non-hazardous drinking) and 48% (predicting AUD severity decrease), in both cases with higher sensitivity than specificity.

    Conclusions: Data from a non-mandatory alcohol consumption diary, adjusted for missing entries, approximates follow-up data at a group level, suggesting that such data can be used to reveal trajectories and processes during treatment and possibly be used to impute missing follow-up data. At an individual level, however, calendar data from the first half of the intervention did not have high predictive accuracy, presumable due to a high rate of missing data and unclear missing mechanisms.

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  • 38.
    Liv, Per
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Svendsen, Susanne Wulff
    Dansih Ramazzini Centre, Herning Hospital, Denmark.
    Accuracy and precision of variance components in occupational posture recordings: a simulation study of different data collection strategies2012In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 12, no 1, p. 58-58Article in journal (Refereed)
    Abstract [en]

    Background. Information on exposure variability, expressed as exposure variance components, is of vital use in occupational epidemiology, including informed risk control and efficient study design. While accurate and precise estimates of the variance components are desirable in such cases, very little research has been devoted to understanding the performance of data sampling strategies designed specifically to determine the size and structure of exposure variability. The aim of this study was to investigate the accuracy and precision of estimators of betweensubjects, between-days and within-day variance components obtained by sampling strategies differing with respect to number of subjects, total sampling time per subject, number of days per subject and the size of individual sampling periods.

    Methods. Minute-by-minute values of average elevation, percentage time above 90degrees and percentage time below 15degrees were calculated in a data set consisting of measurements of right upper arm elevation during four full shifts from each of 23 car mechanics. Based on this parent data, bootstrapping was used to simulate sampling with 80 different combinations of the number of subjects (10, 20), total sampling time per subject (60, 120, 240, 480 minutes), number of days per subject (2, 4), and size of sampling periods (blocks) within days (1, 15, 60, 240 minutes). Accuracy (absence of bias) and precision (prediction intervals) of the variance component estimators were assessed for each simulated sampling strategy.

    Results. Sampling in small blocks within days resulted in essentially unbiased variance components. For a specific total sampling time per subject, and in particular if this time was small, increasing the block size resulted in an increasing bias, primarily of the between-days and the within-days variance components. Prediction intervals were in general wide, and even more so at larger block sizes. Distributing sampling time across more days gave in general more precise variance component estimates, but also reduced accuracy in some cases.

    Conclusions. Variance components estimated from small samples of exposure data within working days may be both inaccurate and imprecise, in particular if sampling is laid out in large consecutive time blocks. In order to estimate variance components with a satisfying accuracy and precision, for instance for arriving at trustworthy power calculations in a planned intervention study, larger samples of data will be required than for estimating an exposure mean value with a corresponding certainty

  • 39.
    Liv, Per
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Mathiassen, Svend Erik
    Svendsen, Susanne Wulff
    Accuracy and precision of variance components in occupational posture recordings: a simulation study of different data collection strategies2012In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 12, p. 58-Article in journal (Refereed)
    Abstract [en]

    Background: Information on exposure variability, expressed as exposure variance components, is of vital use in occupational epidemiology, including informed risk control and efficient study design. While accurate and precise estimates of the variance components are desirable in such cases, very little research has been devoted to understanding the performance of data sampling strategies designed specifically to determine the size and structure of exposure variability. The aim of this study was to investigate the accuracy and precision of estimators of between-subjects, between-days and within-day variance components obtained by sampling strategies differing with respect to number of subjects, total sampling time per subject, number of days per subject and the size of individual sampling periods.

    Methods: Minute-by-minute values of average elevation, percentage time above 90 degrees and percentage time below 15 degrees were calculated in a data set consisting of measurements of right upper arm elevation during four full shifts from each of 23 car mechanics. Based on this parent data, bootstrapping was used to simulate sampling with 80 different combinations of the number of subjects (10, 20), total sampling time per subject (60, 120, 240, 480 minutes), number of days per subject (2, 4), and size of sampling periods (blocks) within days (1, 15, 60, 240 minutes). Accuracy (absence of bias) and precision (prediction intervals) of the variance component estimators were assessed for each simulated sampling strategy.

    Results: Sampling in small blocks within days resulted in essentially unbiased variance components. For a specific total sampling time per subject, and in particular if this time was small, increasing the block size resulted in an increasing bias, primarily of the between-days and the within-days variance components. Prediction intervals were in general wide, and even more so at larger block sizes. Distributing sampling time across more days gave in general more precise variance component estimates, but also reduced accuracy in some cases.

    Conclusions: Variance components estimated from small samples of exposure data within working days may be both inaccurate and imprecise, in particular if sampling is laid out in large consecutive time blocks. In order to estimate variance components with a satisfying accuracy and precision, for instance for arriving at trustworthy power calculations in a planned intervention study, larger samples of data will be required than for estimating an exposure mean value with a corresponding certainty.

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  • 40.
    Lundström, Filip
    et al.
    Department of Otorhinolaryngology, Linköping University Hospital, Linköping, Sweden; Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden.
    Odhagen, Erik
    Department of Otorhinolaryngology, Södra Älvsborgs Hospital, Borås, Sweden; Department of Research, Education and Innovation, Södra Älvsborgs Hospital, Borås, Sweden.
    Alm, Fredrik
    Örebro University, School of Health Sciences.
    Hemlin, Claes
    Department of Otorhinolaryngology, Aleris Sollentuna, Sollentuna, Sweden.
    Nerfeldt, Pia
    Department of Otorhinolaryngology, Karolinska University Hospital, Stockholm, Sweden; Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden .
    Sunnergren, Ola
    Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden; Department of Otorhinolaryngology, Region Jönköping County, Jönköping, Sweden.
    A validation study of data in the National Tonsil Surgery Register in Sweden: high agreement with medical records ensures that data can be used to monitor clinical practices and outcomes2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, no 1, article id 3Article in journal (Refereed)
    Abstract [en]

    Background: The ambition of the National Tonsil Surgery Register in Sweden (NTSRS) is to improve otorhinolaryngological care by monitoring trends in the clinical practices, complications, and outcomes of tonsil surgery. The NTSRS collects data from both surgeons and patients and provides the participating clinics with daily updated data on a publicly available website. On the website, national and local results can be compared and monitored. The use of NTSRS data necessitates that the data is valid, but the NTSRS has not yet been validated. With approximately half of the registered patients responding to the postoperative questionnaires, an analysis of responders and non-responders is also necessary. The aim of this study was to assess the criterion validity of NTSRS data. Another aim was to compare the characteristics and rates of complications between postoperative questionnaire responders and non-responders.

    Methods: Data in the NTSRS were compared with data in electronic medical records. The 200 most recent surger-ies, up to 31 Dec 2019, in each of 11 surgical units were included. Criterion validity was analysed in terms of observed agreement, Cohens kappa, Gwet’s  AC1, and positive and negative agreement. The sign test was used to analyse systematic differences between the NTSRS and the medical records. Comparisons of rates between groups were made with Fisher’s exact test, the chi-square test, and Fisher’s non-parametric permutation test.

    Results: A total of 1991 registrations were included in the study. All variables showed very high observed agreement ranging from 0.91 to 1.00, and all variables had  AC1 values corresponding to almost perfect agreement. The analysis of questionnaire responders and non-responders showed no statistically significant differences regarding age, indication, or type of surgery. The proportion of women was higher in the responder group. The rate of reoperation due to bleeding was higher in the responder group, but there were no differences regarding other complications.

    Conclusions: The results of this study show that data in the NTSRS have criterion validity. The NTSRS is thus well suited for monitoring the clinical practices and outcomes of tonsil surgery. The quality of the data also implies that the registry can be used in both clinical improvement projects and research.

  • 41.
    Lundström, Filip
    et al.
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Sensory Organs and Communication. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Anaesthetics, Operations and Specialty Surgery Center, Department of Otorhinolaryngology.
    Odhagen, Erik
    Department of Otorhinolaryngology, Södra Älvsborgs Hospital, Borås, Sweden; Department of Research, Education and Innovation, Södra Älvsborgs Hospital, Borås, Sweden.
    Alm, Fredrik
    School of Health Sciences, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
    Hemlin, Claes
    Department of Otorhinolaryngology, Aleris Sollentuna, Sollentuna, Sweden.
    Nerfeldt, Pia
    Department of Otorhinolaryngology, Karolinska University Hospital, Stockholm, Sweden; Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden.
    Sunnergren, Ola
    Linköping University, Department of Biomedical and Clinical Sciences, Division of Sensory Organs and Communication. Linköping University, Faculty of Medicine and Health Sciences. Department of Otorhinolaryngology, Region Jönköping County, Jönköping, Sweden.
    A validation study of data in the National Tonsil Surgery Register in Sweden: High agreement with medical records ensures that data can be used to monitor clinical practices and outcomes2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, no 1, article id 3Article in journal (Refereed)
    Abstract [en]

    Background

    The ambition of the National Tonsil Surgery Register in Sweden (NTSRS) is to improve otorhinolaryngological care by monitoring trends in the clinical practices, complications, and outcomes of tonsil surgery. The NTSRS collects data from both surgeons and patients and provides the participating clinics with daily updated data on a publicly available website. On the website, national and local results can be compared and monitored. The use of NTSRS data necessitates that the data is valid, but the NTSRS has not yet been validated. With approximately half of the registered patients responding to the postoperative questionnaires, an analysis of responders and non-responders is also necessary. The aim of this study was to assess the criterion validity of NTSRS data. Another aim was to compare the characteristics and rates of complications between postoperative questionnaire responders and non-responders.

    Methods

    Data in the NTSRS were compared with data in electronic medical records. The 200 most recent surgeries, up to 31 Dec 2019, in each of 11 surgical units were included. Criterion validity was analysed in terms of observed agreement, Cohens kappa, Gwet’s AC1, and positive and negative agreement. The sign test was used to analyse systematic differences between the NTSRS and the medical records. Comparisons of rates between groups were made with Fisher’s exact test, the chi-square test, and Fisher’s non-parametric permutation test.

    Results

    A total of 1991 registrations were included in the study. All variables showed very high observed agreement ranging from 0.91 to 1.00, and all variables had AC1 values corresponding to almost perfect agreement. The analysis of questionnaire responders and non-responders showed no statistically significant differences regarding age, indication, or type of surgery. The proportion of women was higher in the responder group. The rate of reoperation due to bleeding was higher in the responder group, but there were no differences regarding other complications.

    Conclusions

    The results of this study show that data in the NTSRS have criterion validity. The NTSRS is thus well suited for monitoring the clinical practices and outcomes of tonsil surgery. The quality of the data also implies that the registry can be used in both clinical improvement projects and research.

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  • 42.
    Mathiassen, Svend Erik
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Bolin, Kristian
    Department of Economics, Lund University.
    Optimizing cost-efficiency in mean exposure assessment – cost functions reconsidered2011In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 11, no 76Article in journal (Refereed)
    Abstract [en]

    Background. Reliable exposure data is a vital concern in medical epidemiology and intervention studies. The present study addresses the needs of the medical researcher to spend monetary resources devoted to exposure assessment with an optimal cost-efficiency, i.e. obtain the best possible statistical performance at a specified budget. A few previous studies have suggested mathematical optimization procedures based on very simple cost models; this study extends the methodology to cover even non-linear cost scenarios.

    Methods. Statistical performance, i.e. efficiency, was assessed in terms of the precision of an exposure mean value, as determined in a hierarchical, nested measurement model with three stages. Total costs were assessed using a corresponding three-stage cost model, allowing costs at each stage to vary non-linearly with the number of measurements, according to a power function. Using these models, procedures for identifying the optimally cost-efficient allocation of measurements under a constrained budget were developed, and applied on 225 scenarios combining different sizes of unit costs, cost function exponents, and exposure variance components.

    Results. Explicit mathematical rules for identifying optimal allocation could be developed when cost functions were linear, while non-linear cost functions implied that parts of or the entire optimization procedure had to be carried out using numerical methods.

    For many of the 225 scenarios, the optimal strategy consisted in measuring on one occasion from each of as many subjects as allowed by the budget. Significant deviations from this principle occurred if costs for recruiting subjects were large compared to costs for setting up measurement occasions, and, at the same time, the between-subjects to within-subject variance ratio was small. In these cases, non-linearities had a profound influence on the optimal allocation and on the eventual size of the exposure data set.

    Conclusions. The analysis procedures developed in the present study can be used for informed design of exposure assessment strategies, provided that data are available on exposure variability and the costs of collecting and processing data.  The present shortage of empirical evidence on costs and appropriate cost functions however impedes general conclusions on optimal exposure measurement strategies in different epidemiologic scenarios.

  • 43. Mathiassen, Svend Erik
    et al.
    Wahlström, Jens
    Forsman, Mikael
    Bias and imprecision in posture percentile variables estimated from short exposure samples2012In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 12, no 1, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Background

    Upper arm postures are believed to be an important risk determinant for musculoskeletal disorder development in the neck and shoulders. The 10th and 90th percentiles of the angular elevation distribution have been reported in many studies as measures of neutral and extreme postural exposures, and variation has been quantified by the 10th-90th percentile range. Further, the 50th percentile is commonly reported as a measure of "average" exposure. These four variables have been estimated using samples of observed or directly measured postures, typically using sampling durations between 5 and 120 min.

    Methods

    The present study examined the statistical properties of estimated full-shift values of the 10th, 50th and 90th percentile and the 10th-90th percentile range of right upper arm elevation obtained from samples of seven different durations, ranging from 5 to 240 min. The sampling strategies were realized by simulation, using a parent data set of 73 full-shift, continuous inclinometer recordings among hairdressers. For each shift, sampling duration and exposure variable, the mean, standard deviation and sample dispersion limits (2.5% and 97.5%) of all possible sample estimates obtained at one minute intervals were calculated and compared to the true full-shift exposure value.

    Results

    Estimates of the 10th percentile proved to be upward biased with limited sampling, and those of the 90th percentile and the percentile range, downward biased. The 50th percentile was also slightly upwards biased. For all variables, bias was more severe with shorter sampling durations, and it correlated significantly with the true full-shift value for the 10th and 90th percentiles and the percentile range. As expected, shorter samples led to decreased precision of the estimate; sample standard deviations correlated strongly with true full-shift exposure values.

    Conclusions

    The documented risk of pronounced bias and low precision of percentile estimates obtained from short posture samples presents a concern in ergonomics research and practice, and suggests that alternative, unbiased exposure variables should be considered if data collection resources are restricted.

  • 44. Mathiassen, Svend Erik
    et al.
    Wahlström, Jens
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Forsman, Mikael
    Bias and imprecision in posture percentile variables estimated from short exposure samples2012In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 12, p. 36-Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Upper arm postures are believed to be an important risk determinant for musculoskeletal disorder development in the neck and shoulders. The 10th and 90th percentiles of the angular elevation distribution have been reported in many studies as measures of neutral and extreme postural exposures, and variation has been quantified by the 10th-90th percentile range. Further, the 50th percentile is commonly reported as a measure of "average" exposure. These four variables have been estimated using samples of observed or directly measured postures, typically using sampling durations between 5 and 120 min.

    METHODS: The present study examined the statistical properties of estimated full-shift values of the 10th, 50th and 90th percentile and the 10th-90th percentile range of right upper arm elevation obtained from samples of seven different durations, ranging from 5 to 240 min. The sampling strategies were realized by simulation, using a parent data set of 73 full-shift, continuous inclinometer recordings among hairdressers. For each shift, sampling duration and exposure variable, the mean, standard deviation and sample dispersion limits (2.5% and 97.5%) of all possible sample estimates obtained at one minute intervals were calculated and compared to the true full-shift exposure value.

    RESULTS: Estimates of the 10th percentile proved to be upward biased with limited sampling, and those of the 90th percentile and the percentile range, downward biased. The 50th percentile was also slightly upwards biased. For all variables, bias was more severe with shorter sampling durations, and it correlated significantly with the true full-shift value for the 10th and 90th percentiles and the percentile range. As expected, shorter samples led to decreased precision of the estimate; sample standard deviations correlated strongly with true full-shift exposure values.

    CONCLUSIONS: The documented risk of pronounced bias and low precision of percentile estimates obtained from short posture samples presents a concern in ergonomics research and practice, and suggests that alternative, unbiased exposure variables should be considered if data collection resources are restricted.

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  • 45.
    Mathiassen, Svend Erik
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Wahlström, Jens
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Forsman, Mikael
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Bias and imprecision in posture percentile variables estimated from short exposure samples2012In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 12, p. 36-Article in journal (Refereed)
    Abstract [en]

    Background. Upper arm postures are believed to be an important risk determinant for musculoskeletal disorder development in the neck and shoulders. The 10th and 90th percentiles of the angular elevation distribution have been reported in many studies as measures of neutral and extreme postural exposures, and variation has been quantified by the 10th-90th percentile range. Further, the 50th percentile is commonly reported as a measure of "average" exposure. These four variables have been estimated using samples of observed or directly measured postures, typically using sampling durations between 5 and 120 min.

    Methods. The present study examined the statistical properties of estimated full-shift values of the 10th, 50th and 90th percentile and the 10th-90th percentile range of right upper arm elevation obtained from samples of seven different durations, ranging from 5 to 240 min. The sampling strategies were realized by simulation, using a parent data set of 73 full-shift, continuous inclinometer recordings among hairdressers. For each shift, sampling duration and exposure variable, the mean, standard deviation and sample dispersion limits (2.5% and 97.5%) of all possible sample estimates obtained at one minute intervals were calculated and compared to the true full-shift exposure value.

    Results. Estimates of the 10th percentile proved to be upward biased with limited sampling, and those of the 90th percentile and the percentile range, downward biased. The 50th percentile was also slightly upwards biased. For all variables, bias was more severe with shorter sampling durations, and it correlated significantly with the true full-shift value for the 10th and 90th percentiles and the percentile range. As expected, shorter samples led to decreased precision of the estimate; sample standard deviations correlated strongly with true full-shift exposure values.

    Conclusions. The documented risk of pronounced bias and low precision of percentile estimates obtained from short posture samples presents a concern in ergonomics research and practice, and suggests that alternative, unbiased exposure variables should be considered if data collection resources are restricted.

  • 46. May, Anne M.
    et al.
    Adema, Lotte E.
    Romaguera, Dora
    Vergnaud, Anne-Claire
    Agudo, Antonio
    Ekelund, Ulf
    Steffen, Annika
    Orfanos, Philippos
    Slimani, Nadia
    Rinaldi, Sabina
    Mouw, Traci
    Rohrmann, Sabine
    Hermann, Silke
    Boeing, Heiner
    Bergmann, Manuela M.
    Jakobsen, Marianne Uhre
    Overvad, Kim
    Wareham, Nicholas J.
    Gonzalez, Carlos
    Tjonneland, Anne
    Halkjaer, Jytte
    Key, Timothy J.
    Spencer, Elizabeth A.
    Hellström, Veronica
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Nutritional Research.
    Manjer, Jonas
    Hedblad, Bo
    Lund, Eiliv
    Braaten, Tonje
    Clavel-Chapelon, Françoise
    Boutron-Ruault, Marie-Christine
    Rodriguez, Laudina
    Sánchez, Maria J.
    Dorronsoro, Miren
    Barricarte, Aurelio
    Maria Huerta, Jose
    Naska, Androniki
    Trichopoulou, Antonia
    Palli, Domenico
    Pala, Valeria
    Norat, Teresa
    Mattiello, Amalia
    Tumino, Rosario
    van der Daphne, A.
    Bueno-de-Mesquita, H. Bas
    Riboli, Elio
    Peeters, Petra H. M.
    Determinants of non- response to a second assessment of lifestyle factors and body weight in the EPIC-PANACEA study2012In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 12, article id 148Article in journal (Refereed)
    Abstract [en]

    Background: This paper discusses whether baseline demographic, socio-economic, health variables, length of follow-up and method of contacting the participants predict non-response to the invitation for a second assessment of lifestyle factors and body weight in the European multi-center EPIC-PANACEA study. Methods: Over 500.000 participants from several centers in ten European countries recruited between 1992 and 2000 were contacted 2-11 years later to update data on lifestyle and body weight. Length of follow-up as well as the method of approaching differed between the collaborating study centers. Non-responders were compared with responders using multivariate logistic regression analyses. Results: Overall response for the second assessment was high (81.6%). Compared to postal surveys, centers where the participants completed the questionnaire by phone attained a higher response. Response was also high in centers with a short follow-up period. Non-response was higher in participants who were male (odds ratio 1.09 (confidence interval 1.07; 1.11), aged under 40 years (1.96 (1.90; 2.02), living alone (1.40 (1.37; 1.43), less educated (1.35 (1.12; 1.19), of poorer health (1.33 (1.27; 1.39), reporting an unhealthy lifestyle and who had either a low (<18.5 kg/m2, 1.16 (1.09; 1.23)) or a high BMI (>25, 1.08 (1.06; 1.10); especially >= 30 kg/m2, 1.26 (1.23; 1.29)). Conclusions: Cohort studies may enhance cohort maintenance by paying particular attention to the subgroups that are most unlikely to respond and by an active recruitment strategy using telephone interviews.

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  • 47.
    Nilsson, Anton
    et al.
    Lund University, Sweden.
    Björk, Jonas
    Lund University, Sweden; Skåne University Hospital, Sweden.
    Strömberg, Ulf
    University of Gothenburg, Sweden.
    Bonander, Carl
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Center for Societal Risk Research, CSR (from 2020). University of Gothenburg, Sweden.
    Can non-participants in a follow-up be used to draw conclusions about incidences and prevalences in the full population invited at baseline?: An investigation based on the Swedish MDC cohort2023In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 23, no 1, article id 228Article in journal (Refereed)
    Abstract [en]

    Background: Participants in epidemiological cohorts may not be representative of the full invited population, limiting the generalizability of prevalence and incidence estimates. We propose that this problem can be remedied by exploiting data on baseline participants who refused to participate in a re-examination, as such participants may be more similar to baseline non-participants than what baseline participants who agree to participate in the re-examination are. Methods: We compared background characteristics, mortality, and disease incidences across the full population invited to the Malmö Diet and Cancer (MDC) study, the baseline participants, the baseline non-participants, the baseline participants who participated in a re-examination, and the baseline participants who did not participate in the re-examination. We then considered two models for estimating characteristics and outcomes in the full population: one (“the substitution model”) assuming that the baseline non-participants were similar to the baseline participants who refused to participate in the re-examination, and one (“the extrapolation model”) assuming that differences between the full group of baseline participants and the baseline participants who participated in the re-examination could be extended to infer results in the full population. Finally, we compared prevalences of baseline risk factors including smoking, risky drinking, overweight, and obesity across baseline participants, baseline participants who participated in the re-examination, and baseline participants who did not participate in the re-examination, and used the above models to estimate the prevalences of these factors in the full invited population. Results: Compared to baseline non-participants, baseline participants were less likely to be immigrants, had higher socioeconomic status, and lower mortality and disease incidences. Baseline participants not participating in the re-examination generally resembled the full population. The extrapolation model often generated characteristics and incidences even more similar to the full population. The prevalences of risk factors, particularly smoking, were estimated to be substantially higher in the full population than among the baseline participants. Conclusions: Participants in epidemiological cohorts such as the MDC study are unlikely to be representative of the full invited population. Exploiting data on baseline participants who did not participate in a re-examination can be a simple and useful way to improve the generalizability of prevalence and incidence estimates. 

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  • 48.
    Norström, Fredrik
    et al.
    Umeå University, Faculty of Medicine, Department of Epidemiology and Global Health.
    Hammarström, Anne
    Umeå University, Faculty of Medicine, Department of Epidemiology and Global Health. Institute of Environmental Medicine, Occupational Medicine, Karolinska Institutet, Stockholm, Sweden.
    Methodological perspectives on the study of the health effects of unemployment – reviewing the mode of unemployment, the statistical analysis method and the role of confounding factors2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, no 1, article id 199Article in journal (Refereed)
    Abstract [en]

    Introduction: Studying the relationship between unemployment and health raises many methodological challenges. In the current study, the aim was to evaluate the sensitivity of estimates based on different ways of measuring unemployment and the choice of statistical model.

    Methods: The Northern Swedish cohort was used, and two follow-up surveys thereof from 1995 and 2007, as well as register data about unemployment. Self-reported current unemployment, self-reported accumulated unemployment and register-based accumulated unemployment were used to measure unemployment and its effect on self-reported health was evaluated. Analyses were conducted with G-computation, logistic regression and three estimators for the inverse probability weighting propensity scores, and 11 potentially confounding variables were part of the analyses. Results were presented with absolute differences in the proportion with poor self-reported health between unemployed and employed individuals, except when logistic regression was used alone.

    Results: Of the initial 1083 pupils in the cohort, our analyses vary between 488–693 individuals defined as employed and 61–214 individuals defined as unemployed. In the analyses, the deviation was large between the unemployment measures, with a difference of at least 2.5% in effect size when unemployed was compared with employed for the self-reported and register-based unemployment modes. The choice of statistical method only had a small influence on effect estimates and the deviation was in most cases lower than 1%. When models were compared based on the choice of potential confounders in the analytical model, the deviations were rarely above 0.6% when comparing models with 4 and 11 potential confounders. Our variable for health selection was the only one that strongly affected estimates when it was not part of the statistical model.

    Conclusions: How unemployment is measured is highly important when the relationship between unemployment and health is estimated. However, misspecifications of the statistical model or choice of analytical method might not matter much for estimates except for the inclusion of a variable measuring health status before becoming unemployed. Our results can guide researchers when analysing similar research questions. Model diagnostics is commonly lacking in publications, but they remain very important for validation of analyses.

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  • 49.
    Olsson, Karin Sofia Elisabeth
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Rosdahl, Hans
    Swedish School of Sport and Health Sciences, GIH, Department of Physiology, Nutrition and Biomechanics.
    Schantz, Peter
    Swedish School of Sport and Health Sciences, GIH, Department of Physical Activity and Health.
    Interchangeability and optimization of heart rate methods for estimating oxygen uptake in ergometer cycling, level treadmill walking and running.2022In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 22, no 1, article id 55Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: The heart rate (HR) method enables estimating oxygen uptake (V̇O2) in physical activities. However, there is a paucity in knowledge about the interchangeability of this method when applied to cycling, walking and running. Furthermore, with the aim of optimization, there is a need to compare different models for establishing HR-V̇O2 relationships.

    METHODS: Twenty-four physically active individuals (12 males and 12 females) participated. For each participant, two models of HR-V̇O2 relationships were individually established in ergometer cycling, level treadmill walking and running. Model 1 consisted of five submaximal workloads, whereas model 2 included also a maximal workload. Linear regression equations were used to estimate V̇O2 at seven intensity levels ranging between 25 and 85% of heart rate reserve (HRR). The estimated V̇O2 levels were compared between the exercise modalities and models, as well as with data from a previous study.

    RESULTS: A high level of resemblance in estimated V̇O2 was noted between running and cycling as well as between running and walking, with both model 1 and model 2. When comparing walking and cycling, the V̇O2 levels for given intensities of %HRR were frequently slightly higher in walking with both models (range of significant differences: 5-12%). The variations of the estimated individual V̇O2 values were reduced when using model 2 compared to model 1, both between and within the exercise modalities.

    CONCLUSION: The HR method is optimized by more workloads and wider ranges. This leads to overall high levels of interchangeability when HR methods are applied in ergometer cycling, level treadmill walking and running.

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  • 50. Pearce, Michael
    et al.
    Hee, Siew Wan
    Madan, Jason
    Posch, Martin
    Day, Simon
    Miller, Frank
    Stockholm University, Faculty of Social Sciences, Department of Statistics.
    Zohar, Sarah
    Stallard, Nigel
    Value of information methods to design a clinical trial in a small population to optimise a health economic utility function2018In: BMC Medical Research Methodology, E-ISSN 1471-2288, Vol. 18, article id 20Article in journal (Refereed)
    Abstract [en]

    Background: Most confirmatory randomised controlled clinical trials (RCTs) are designed with specified power, usually 80% or 90%, for a hypothesis test conducted at a given significance level, usually 2.5% for a one-sided test. Approval of the experimental treatment by regulatory agencies is then based on the result of such a significance test with other information to balance the risk of adverse events against the benefit of the treatment to future patients. In the setting of a rare disease, recruiting sufficient patients to achieve conventional error rates for clinically reasonable effect sizes may be infeasible, suggesting that the decision-making process should reflect the size of the target population. Methods: We considered the use of a decision-theoretic value of information (VOI) method to obtain the optimal sample size and significance level for confirmatory RCTs in a range of settings. We assume the decision maker represents society. For simplicity we assume the primary endpoint to be normally distributed with unknown mean following some normal prior distribution representing information on the anticipated effectiveness of the therapy available before the trial. The method is illustrated by an application in an RCT in haemophilia A. We explicitly specify the utility in terms of improvement in primary outcome and compare this with the costs of treating patients, both financial and in terms of potential harm, during the trial and in the future. Results: The optimal sample size for the clinical trial decreases as the size of the population decreases. For non-zero cost of treating future patients, either monetary or in terms of potential harmful effects, stronger evidence is required for approval as the population size increases, though this is not the case if the costs of treating future patients are ignored. Conclusions: Decision-theoretic VOI methods offer a flexible approach with both type I error rate and power (or equivalently trial sample size) depending on the size of the future population for whom the treatment under investigation is intended. This might be particularly suitable for small populations when there is considerable information about the patient population.

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