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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, ISSN 1471-2288, 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.

  • 2.
    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, ISSN 1471-2288, 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.

  • 3.
    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, ISSN 1471-2288, 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.

  • 4.
    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, ISSN 1471-2288, 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.

  • 5.
    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, ISSN 1471-2288, 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.

  • 6.
    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, ISSN 1471-2288, 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.

  • 7.
    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, ISSN 1471-2288, 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.

  • 8.
    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, ISSN 1471-2288, 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

  • 9.
    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, ISSN 1471-2288, 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.

  • 10.
    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, ISSN 1471-2288, 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.

  • 11. 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, ISSN 1471-2288, 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.

  • 12.
    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, ISSN 1471-2288, 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.

  • 13. 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, ISSN 1471-2288, 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).

  • 14.
    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, ISSN 1471-2288, 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.

  • 15.
    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, ISSN 1471-2288, 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

  • 16.
    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, ISSN 1471-2288, 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.

  • 17.
    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, ISSN 1471-2288, 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.

  • 18. 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, ISSN 1471-2288, 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.

  • 19.
    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, ISSN 1471-2288, 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.

  • 20. 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, ISSN 1471-2288, 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.

  • 21. 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, ISSN 1471-2288, 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.

  • 22.
    Samani, Afshin
    et al.
    Center for Sensory Motor Interaction, Department of Health Science and Technology, Aalborg University.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Madeleine, Pascal
    Center for Sensory Motor Interaction, Department of Health Science and Technology, Aalborg University.
    Cluster-based exposure variation analysis2013In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 13, p. 54-54Article in journal (Refereed)
    Abstract [en]

    Background: Static posture, repetitive movements and lack of physical variation are known risk factors for work-related musculoskeletal disorders, and thus needs to be properly assessed in occupational studies. The aims of this study were (i) to investigate the effectiveness of a conventional exposure variation analysis (EVA) in discriminating exposure time lines and (ii) to compare it with a new cluster-based method for analysis of exposure variation.

    Methods: For this purpose, we simulated a repeated cyclic exposure varying within each cycle between “low” and “high” exposure levels in a “near” or “far” range, and with  “low” or “high” velocities (exposure change rates). The duration of each cycle was also manipulated by selecting a “small” or “large” standard deviation of the cycle time. Theses parameters reflected three dimensions of exposure variation, i.e. range, frequency and temporal similarity. Each simulation trace included two realizations of 100 concatenated cycles with either low (r=0.1), medium (r=0.5) or high (r=0.9) correlation between the realizations. These traces were analyzed by conventional EVA, and a novel cluster-based EVA (C-EVA). Principal component analysis (PCA) was applied on the marginal distributions of 1) the EVA of each of the realizations (univariate approach), 2) a combination of the EVA of both realizations (multivariate approach) and 3) C-EVA. The least number of principal components describing more than 90% of variability in each case was selected and the projection of marginal distributions along the selected principal component was calculated. A linear classifier was then applied to these projections to discriminate between the simulated exposure patterns, and the accuracy of classified realizations was determined.

    Results: C-EVA classified exposures more correctly than uni 1 variate and multivariate EVA approaches; classification accuracy was 49%, 47% and 52% for EVA (univariate and multivariate), and C-EVA, respectively (p<0.001). All three methods performed poorly in discriminating exposure patterns differing with respect to the variability in cycle time duration.

    Conclusion: While C-EVA had a higher accuracy than conventional EVA, both failed to detect differences in temporal similarity. The data-driven optimality of data reduction and the capability of handling multiple exposure time lines in a single analysis are the advantages of the C-EVA.

  • 23.
    Svedberg, Petra
    et al.
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI), Health promotion and disease prevention.
    Nygren, Jens
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI), Health promotion and disease prevention.
    Staland Nyman, Carin
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    Nyholm, Maria
    Halmstad University, School of Health and Welfare, Centre of Research on Welfare, Health and Sport (CVHI).
    The validity of socioeconomic status measures among adolescents based on self-reported information about parents occupations, FAS and perceived SES; implication for health related quality of life studies2016In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 16, article id 48Article in journal (Refereed)
    Abstract [en]

    Background

    Research has shown inconsistencies in results and difficulties in conceptualization of assessment of socioeconomic status (SES) among adolescents. The aim of this study was thus to test the validity of self-reported information on SES in two age-groups (11–13 and 14–16 years old) in an adolescent population and to evaluate its relationship to self-reported health related quality of life (HRQOL). Different measures of SES commonly used in research in relation to HRQOL were tested in this study; parent’s occupations status, family material affluence status (FAS) and perceived SES.

    Method

    A cross-sectional study, with a sample of 948 respondents (n = 467, 11–13 years old and n  = 481, 14–16 years old) completed questionnaires about SES and HRQOL. The adolescents’ completion rates were used, with chi2-test, to investigate differences between gender and age-group. Correlation was used for convergent validity and ANOVA for concurrent validity.

    Results

    We found a low completion rate for both fathers’ (41.7 %) and mothers' (37.5 %) occupation status, and a difference in completion rate between gender and age-groups. FAS had the highest completion rate (100 %) compared to parent's occupations status and perceived SES. The convergent validity between the SES-indicators was weak (Spearman correlation coefficient below 0.3), suggesting that the indicators measured different dimensions of SES. Both FAS and perceived SES showed a gradient in mean HRQOL between low and high SES in relation to HRQOL, this was significant only for perceived SES (p < 0.01, both age-groups).

    Conclusion

    This study indicates the need for considering different approaches to measures of SES among adolescences and when evaluating SES in relation to HRQOL. Further research is needed to investigate sustainable ways to measure SES, delineating the relevance of tangible measures of education, occupation and income in relation to the perceived socioeconomic status in comparison with others in immediate social networks and in society at large.

  • 24.
    Trask, Catherine
    et al.
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research. University of Saskatchewan, College of Medicine, Centre for Health & Safety in Agriculture, Saskatoon, SK S7N 0W8, Canada.
    Mathiassen, Svend Erik
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. University of Gävle, Centre for Musculoskeletal Research.
    Jackson, Jennie
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, Occupational health science. 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, Occupational health science. University of Gävle, Centre for Musculoskeletal Research. Umea University, Department of Public Health & Clinical Medical Occupational & Environmental Medicine, SE-90185 UmeåSweden.
    Data processing costs for three posture assessment methods2013In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 13, no 1, p. 124-Article in journal (Refereed)
    Abstract [en]

    Objectives. Data processing contributes a non-trivial proportion to total research costs, but documentation of these costs is rare. This paper employed a priori cost tracking for three posture assessment methods (self-report, observation of video, and inclinometry), developed a model describing the fixed and variable cost components, and simulated additional study scenarios to demonstrate the utility of the model. 

    Methods. Trunk and shoulder postures of aircraft baggage handlers were assessed for 80 working days using all three methods. A model was developed to estimate data processing phase costs, including fixed and variable components related to study planning and administration, custom software development, training of analysts, and processing time.   

    Results. Observation of video was the most costly data processing method with total cost of 31,433, and was 1.2-fold more costly than inclinometry (€ 26,255), and 2.5-fold more costly than self-reported data (€ 12,491). Simulated scenarios showed altering design strategy could substantially impact processing costs. This was shown for both fixed parameters, such as software development and training costs, and variable parameters, such as the number of work-shift files processed, as well as the sampling frequency for video observation.  When data collection and data processing costs were combined, the cost difference between video and inclinometer methods was reduced to 7%; simulated data showed this difference could be diminished and, even, reversed at larger study sample sizes. Self-report remained substantially less costly under all design strategies, but produced alternate exposure metrics. 

    Conclusions. These findings build on the previously published data collection phase cost model by reporting costs for post-collection data processing of the same data set.  Together, these models permit empirically based study planning and identification of cost-efficient study designs.

  • 25. Trask, Catherine
    et al.
    Mathiassen, Svend Erik
    Jackson, Jennie
    Wahlström, Jens
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Data processing costs for three posture assessment methods2013In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 13, article id 124Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Data processing contributes a non-trivial proportion to total research costs, but documentation of these costs is rare. This paper employed a priori cost tracking for three posture assessment methods (self-report, observation of video, and inclinometry), developed a model describing the fixed and variable cost components, and simulated additional study scenarios to demonstrate the utility of the model.

    METHODS: Trunk and shoulder postures of aircraft baggage handlers were assessed for 80 working days using all three methods. A model was developed to estimate data processing phase costs, including fixed and variable components related to study planning and administration, custom software development, training of analysts, and processing time.

    RESULTS: Observation of video was the most costly data processing method with total cost of € 30,630, and was 1.2-fold more costly than inclinometry (€ 26,255), and 2.5-fold more costly than self-reported data (€ 12,491). Simulated scenarios showed altering design strategy could substantially impact processing costs. This was shown for both fixed parameters, such as software development and training costs, and variable parameters, such as the number of work-shift files processed, as well as the sampling frequency for video observation. When data collection and data processing costs were combined, the cost difference between video and inclinometer methods was reduced to 7%; simulated data showed this difference could be diminished and, even, reversed at larger study sample sizes. Self-report remained substantially less costly under all design strategies, but produced alternate exposure metrics.

    CONCLUSIONS: These findings build on the previously published data collection phase cost model by reporting costs for post-collection data processing of the same data set. Together, these models permit empirically based study planning and identification of cost-efficient study designs.

  • 26.
    Trask, Catherine
    et al.
    Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden.
    Mathiassen, Svend Erik
    Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden.
    Wahlström, Jens
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Occupational and Environmental Medicine.
    Heiden, Marina
    Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden.
    Rezagholi, Mahmoud
    Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gävle, Gävle, Sweden.
    Data collection costs in industrial environments for three occupational posture exposure assessment methods2012In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 12, no 1, p. 89-Article in journal (Refereed)
    Abstract [en]

    Background: Documentation of posture measurement costs is rare and cost models that do exist are generally nave. This paper provides a comprehensive cost model for biomechanical exposure assessment in occupational studies, documents the monetary costs of three exposure assessment methods for different stakeholders in data collection, and uses simulations to evaluate the relative importance of cost components. Methods: Trunk and shoulder posture variables were assessed for 27 aircraft baggage handlers for 3 full shifts each using three methods typical to ergonomic studies: self-report via questionnaire, observation via video film, and full-shift inclinometer registration. The cost model accounted for expenses related to meetings to plan the study, administration, recruitment, equipment, training of data collectors, travel, and onsite data collection. Sensitivity analyses were conducted using simulated study parameters and cost components to investigate the impact on total study cost. Results: Inclinometry was the most expensive method (with a total study cost of (sic) 66,657), followed by observation ((sic) 55,369) and then self report ((sic) 36,865). The majority of costs (90%) were borne by researchers. Study design parameters such as sample size, measurement scheduling and spacing, concurrent measurements, location and travel, and equipment acquisition were shown to have wide-ranging impacts on costs. Conclusions: This study provided a general cost modeling approach that can facilitate decision making and planning of data collection in future studies, as well as investigation into cost efficiency and cost efficient study design. Empirical cost data from a large field study demonstrated the usefulness of the proposed models.

  • 27.
    Trask, Catherine
    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.
    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.
    Heiden, Marina
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Rezagholi, Mahmoud
    University of Gävle, Faculty of Health and Occupational Studies, Department of Occupational and Public Health Sciences, CBF. University of Gävle, Centre for Musculoskeletal Research.
    Data collection costs in industrial environments for three occupational posture exposure assessment methods2012In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 12, p. 89-Article in journal (Refereed)
    Abstract [en]

    Background. Documentation of posture measurement costs is rare and cost models that do exist are generally naïve. This paper provides a comprehensive cost model for biomechanical exposure assessment in occupational studies, documents the monetary costs of three exposure assessment methods for different stakeholders in data collection, and uses simulations to evaluate the relative importance of cost components.  Trunk and shoulder posture variables were assessed for 27 aircraft baggage handlers for 3 full shifts each using three methods typical to ergonomic studies: self-report via questionnaire, observation via video film, and full-shift inclinometer registration.  The cost model accounted for expenses related to meetings to plan the study, administration, recruitment, equipment, training of data collectors, travel, and onsite data collection.  Sensitivity analyses were conducted using simulated study parameters and cost components to investigate the impact on total study cost.

    Results. Inclinometery was the most expensive method (with a total study cost of € 66,657), followed by observation (€ 55,369) and then self report (€ 36,865). The majority of costs (90%) were borne by researchers.  Study design parameters such as sample size, measurement scheduling and spacing, concurrent measurements, location and travel, and equipment acquisition were shown to have wide-ranging impacts on costs. 

    Conclusions. This study provided a general cost modelling approach that can facilitate decision making and planning of data collection in future studies, as well as investigation into cost efficiency and cost efficient study design. Empirical cost data from a large field study demonstrated the usefulness of the proposed models.

  • 28.
    Valaker, Irene
    et al.
    Western Norway Univ Appl Sci, Norway.
    Fridlund, Bengt
    Linnaeus University, Faculty of Health and Life Sciences, Department of Health and Caring Sciences. Haukeland Hosp, Norway.
    Wentzel-Larsen, Tore
    Haukeland Hosp, Norway;Ctr Child & Adolescent Mental Hlth Eastern & Sout, Norway;Norwegian Ctr Violence & Traumat Stress Studies, Norway.
    Hadjistavropoulos, Heather
    Univ Regina, Canada.
    Nordrehaug, Jan Erik
    Univ Bergen, Norway;Stavanger Univ Hosp, Norway.
    Rotevatn, Svein
    Haukeland Hosp, Norway;Norwegian Registry Invas Cardiol, Norway.
    Raholm, Maj-Britt
    Western Norway Univ Appl Sci, Norway.
    Norekval, Tone M.
    Western Norway Univ Appl Sci, Norway;Haukeland Hosp, Norway;Univ Bergen, Norway.
    Adaptation and psychometric properties of the Norwegian version of the heart continuity of care questionnaire (HCCQ)2019In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 19, p. 1-15, article id 62Article in journal (Refereed)
    Abstract [en]

    Background: Continuity of cardiac care after hospital discharge is a priority, especially as healthcare systems become increasingly complex and fragmented. There are few available instruments to measure continuity of cardiac care, especially from the patient perspective. The aim of this study was (1) to translate and adapt the Heart Continuity of Care Questionnaire (HCCQ) to conditions in Norway, and (2) to determine its psychometric properties in self-report format administered to patients after percutaneous coronary intervention (PCI). Methods: The HCCQ was first translated into Norwegian from the original English version, following a widely used cross-cultural adaptation process. Data were collected before hospital discharge and in a follow-up after 2months. To assess psychometric properties, a confirmatory factor analysis (CFA) was performed and three aspects of construct validity were evaluated: structural validity, hypotheses testing and cross-cultural validation. Internal consistency of the HCCQ subscales was calculated using Cronbach's alpha, while intra-class correlation (ICC) was used to assess test-retest reliability. Additionally, socio-demographic and patient-reported data were collected to correlate with HCCQ scores. Results: Of those included at baseline, 436 (76%) completed the questionnaires after 2months. CFA suggested that the fit of the HCCQ data to a 3-factor model was modest (RMSEA = 0.11, CFI = 0.90, TLI = 0.90). However, convergent validity was satisfactory, based on existing research. Internal consistency was good, as indicated by its Cronbach's alphas: total continuity of care (0.95); informational (0.93), relational (0.87), and management (0.89) continuity. The ICC for the total HCCQ score was 0.80 (95% CI [0.71, 0.87] p<0.001). As indicated by negative care experiences (rated as 1 or 2 on the five-point scale), patients seemed to have limited knowledge about medical treatment, lifestyle modification and follow-up after PCI. Participation in cardiac rehabilitation and longer consultations with the general practitioner after hospital discharge were positively correlated with better continuity of care. Conclusions: Implementation of the HCCQ will likely support healthcare providers and researchers in identifying problem areas of continuity of cardiac care and in evaluating interventions aimed at improving continuity of care.

  • 29.
    Vanhelst, Jérémy
    et al.
    University Lille 2, France ; Toulouse University Hospital, France.
    Béghin, Laurent
    University Lille 2, France ; Toulouse University Hospital, France.
    Duhamel, Alain
    University of Lille Nord de France, France.
    Bergman, Patrick
    Linnaeus University, Faculty of Health, Social Work and Behavioural Sciences, School of Education, Psychology and Sport Science.
    Sjöström, Michael
    Karolinska Institutet.
    Gottrand, Frédéric
    University Lille 2, France.
    Comparison of uniaxial and triaxial accelerometry in the assessment of physical activity among adolescents under free-living conditions: the HELENA study2012In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 12, article id 26Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Different types of devices are available and the choice about which to use depends on various factors: cost, physical characteristics, performance, and the validity and intra- and interinstrument reliability. Given the large number of studies that have used uniaxial or triaxial devices, it is of interest to know whether the different devices give similar information about PA levels and patterns. The aim of this study was to compare physical activity (PA) levels and patterns obtained simultaneously by triaxial accelerometry and uniaxial accelerometry in adolescents in free-living conditions.

    METHODS: Sixty-two participants, aged 13-16 years, were recruited in this ancillary study, which is a part of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA). All participants wore a uniaxial accelerometer (ActiGraph GT1M®, Pensacola, FL) and a triaxial accelerometer (RT3®, Stayhealthy, Monrovia, CA) simultaneously for 7 days. The patterns were calculated by converting accelerometer data output as a percentage of time spent at sedentary, light, moderate, and vigorous PA per day. Analysis of output data from the two accelerometers were assessed by two different tests: Equivalence Test and Bland & Altman method.

    RESULTS: The concordance correlation coefficient between the data from the triaxial accelerometer and uniaxial accelerometer at each intensity level was superior to 0.95. The ANOVA test showed a significant difference for the first three lower intensities while no significant difference was found for vigorous intensity. The difference between data obtained with the triaxial accelerometer and the uniaxial monitor never exceeded 2.1% and decreased as PA level increased. The Bland & Altman method showed good agreement between data obtained between the both accelerometers (p < 0.05).

    CONCLUSIONS: Uniaxial and triaxial accelerometers do not differ in their measurement of PA in population studies, and either could be used in such studies.

  • 30.
    Veldwijk, Jorien
    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.
    Determann, D.
    Lambooij, M.
    van Til, J. A.
    Korfage, I. J.
    de Bekker-Grob, E. W.
    de Wit, A.
    Exploring how individuals complete the choice tasks in a discrete choice experiment: an interview study2016In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 16, no 45Article in journal (Refereed)
    Abstract [en]

    Background

    To be able to make valid inferences on stated preference data from a Discrete Choice Experiment (DCE) it is essential that researchers know if participants were actively involved, understood and interpreted the provided information correctly and whether they used complex decision strategies to make their choices and thereby acted in accordance with the continuity axiom.

    Methods

    During structured interviews, we explored how 70 participants evaluated and completed four discrete choice tasks aloud. Hereafter, additional questions were asked to further explore if participants understood the information that was provided to them and whether they used complex decision strategies (continuity axiom) when making their choices. Two existing DCE questionnaires on rotavirus vaccination and prostate cancer-screening served as case studies.

    Results

    A large proportion of the participants was not able to repeat the exact definition of the risk attributes as explained to them in the introduction of the questionnaire. The majority of the participants preferred more optimal over less optimal risk attribute levels. Most participants (66 %) mentioned three or more attributes when motivating their decisions, thereby acting in accordance with the continuity axiom. However, 16 out of 70 participants continuously mentioned less than three attributes when motivating their decision. Lower educated and less literate participants tended to mention less than three attributes when motivating their decision and used trading off between attributes less often as a decision-making strategy.

    Conclusion

    The majority of the participants seemed to have understood the provided information about the choice tasks, the attributes, and the levels. They used complex decision strategies (continuity axiom) and are therefore capable to adequately complete a DCE. However, based on the participants’ age, educational level and health literacy additional, actions should be undertaken to ensure that participants understand the choice tasks and complete the DCE as presumed.

  • 31.
    von Thiele Schwarz, Ulrica
    et al.
    Mälardalen University, School of Health, Care and Social Welfare, Health and Welfare.
    Förberg, U.
    Karolinska Institutet, Stockholm, Sweden.
    Sundell, K.
    Karolinska Institutet, Stockholm, Sweden.
    Hasson, H.
    Karolinska Institutet, Stockholm, Sweden.
    Colliding ideals - An interview study of how intervention researchers address adherence and adaptations in replication studies2018In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 18, no 1, article id 36Article, review/survey (Refereed)
    Abstract [en]

    Background: For an intervention to be considered evidence-based, findings need to be replicated. When this is done in new contexts (e.g., a new country), adaptations may be needed. Yet, we know little about how researchers approach this. This study aims to explore how researchers reason about adaptations and adherence when conducting replication studies, describe what adaptations they make and how these are reported in scientific journals. Methods: This was an interview study conducted in 2014 with principal investigators of Swedish replication studies reporting adaptations to an intervention from another country. Studies (n = 36) were identified through a database of 139 Swedish psychosocial and psychological intervention studies. Twenty of the 21 principal investigators agreed to participate in semi-structured telephone interviews, covering 33 interventions. Manifest content analysis was used to identify types of adaptations, and qualitative content analysis was used to explore reasoning and reporting of adaptations and adherence. Results: The most common adaptation was adding components and modifying the content to the target population and setting. When reasoning about adaptations and adherence, the researchers were influenced by four main factors: whether their implicit aim was to replicate or improve an intervention; the nature of evidence outlying the intervention such as manuals, theories and core components; the nature of the context, including approaches to cultural adaptations and constraints in delivering the intervention; and the needs of clients and professionals. Reporting of adaptations in scientific journals involved a conflict between transparency and practical concerns such as word count. Conclusions: Researchers responsible for replicating interventions in a new country face colliding ideals when trying to protect the internal validity of the study while considering adaptations to ensure that the intervention fits into the context. Implicit assumptions about the role of replication seemed to influence how this conflict was resolved. Some emphasised direct replications as central in the knowledge accumulation process (stressing adherence). Others assumed that interventions generally need to be improved, giving room for adaptations and reflecting an incremental approach to knowledge accumulation. This has implications for design and reporting of intervention studies as well as for how findings across studies are synthesised. 

  • 32.
    Wahlgren, Lina
    et al.
    Örebro University, School of Health and Medical Sciences.
    Schantz, Peter
    Bikeability and methodological issues using the active commuting route environment scale (ACRES) in a metropolitan setting2011In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 11, article id 6Article in journal (Refereed)
    Abstract [en]

    Background: Route environments can positively influence people’s active commuting and thereby contribute to public health. The Active Commuting Route Environment Scale (ACRES) was developed to study active commuters’ perceptions of their route environments. However, bicycle commuters represent a small portion of the population in many cities and thus are difficult to study using population-based material. Therefore, the aim of this study is to expand the state of knowledge concerning the criterion-related validity of the ACRES and the representativity using an advertisement-recruited sample. Furthermore, by comparing commuting route environment profiles of inner urban and suburban areas, we provide a novel basis for understanding the relationship between environment and bikeability.

    Methods: Bicycle commuters from Greater Stockholm, Sweden, advertisement- (n = 1379) and street-recruited (n = 93), responded to the ACRES. Traffic planning and environmental experts from the Municipality of Stockholm (n = 24) responded to a modified version of the ACRES. The criterion-related validity assessments were based on whether or not differences between the inner urban and the suburban route environments, as indicated by the experts and by four existing objective measurements, were reflected by differences in perceptions of these environments. Comparisons of ratings between advertisement-and street-recruited participants were used for the assessments of representativity. Finally, ratings of inner urban and suburban route environments were used to evaluate commuting route environment profiles.

    Results: Differences in ratings of the inner urban and suburban route environments by the advertisement-recruited participants were in accord with the existing objective measurements and corresponded reasonably well with those of the experts. Overall, there was a reasonably good correspondence between the advertisement-and street-recruited participants’ ratings. Distinct differences in commuting route environment profiles were noted between the inner urban and suburban areas. Suburban route environments were rated as safer and more stimulating for bicycle-commuting than the inner urban ones. In general, the findings applied to both men and women.

    Conclusions: The overall results show: considerable criterion-related validity of the ACRES; ratings of advertisement-recruited participants mirroring those of street-recruited participants; and a higher degree of bikeability in the suburban commuting route environments than in the inner urban ones.

  • 33.
    Wahlgren, Lina
    et al.
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, The Research Unit for Movement, Health and Environment.
    Schantz, Peter
    Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, The Research Unit for Movement, Health and Environment.
    Bikeability and methodological issues using the active commuting route environment scale (ACRES) in a metropolitan setting2011In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 11, no 6Article in journal (Refereed)
    Abstract [en]

    Background Route environments can positively influence people’s active commuting and thereby contribute to public health. The Active Commuting Route Environment Scale (ACRES) was developed to study active commuters’ perceptions of their route environments. However, bicycle commuters represent a small portion of the population in many cities and thus are difficult to study using population-based material. Therefore, the aim of this study is to expand the state of knowledge concerning the criterion-related validity of the ACRES and the representativity using an advertisement-recruited sample. Furthermore, by comparing commuting route environment profiles of inner urban and suburban areas, we provide a novel basis for understanding the relationship between environment and bikeability.

    Methods Bicycle commuters from Greater Stockholm, Sweden, advertisement- (n = 1379) and street-recruited (n = 93), responded to the ACRES. Traffic planning and environmental experts from the Municipality of Stockholm (n = 24) responded to a modified version of the ACRES. The criterion-related validity assessments were based on whether or not differences between the inner urban and the suburban route environments, as indicated by the experts and by four existing objective measurements were reflected by differences in perceptions of these environments. Comparisons of ratings between advertisement- and street-recruited participants were used for the assessments of representativity. Finally, ratings of inner urban and suburban route environments were used to evaluate commuting route environment profiles.

    Results Differences in ratings of the inner urban and suburban route environments by the advertisement-recruited participants were in accord with the existing objective measurements and corresponded reasonably well with those of the experts. Overall, there was a reasonably good correspondence between the advertisement- and street-recruited participants’ ratings. Distinct differences in commuting route environment profiles were noted between the inner urban and suburban areas. Suburban route environments were rated as safer and more stimulating for bicycle-commuting than the inner urban ones. In general, the findings applied to both men and women.

    Conclusions The overall results show: considerable criterion-related validity of the ACRES; ratings of advertisement-recruited participants mirroring those of street-recruited participants; and a higher degree of bikeability in the suburban commuting route environments than in the inner urban ones.

  • 34.
    Wahlgren, Lina
    et al.
    The Swedish School of Sport and Health Sciences, Stockholm, Sweden.
    Schantz, Peter
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Bikeability and methodological issues using the active commuting route environment scale (ACRES) in a metropolitan setting.2011In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 11, no 1, p. 6-Article in journal (Refereed)
    Abstract [en]

    The overall results show: considerable criterion-related validity of the ACRES; ratings of advertisement-recruited participants mirroring those of street-recruited participants; and a higher degree of bikeability in the suburban commuting route environments than in the inner urban ones.

  • 35.
    Waller, Göran
    et al.
    Umeå universitet.
    Thalén, Peder
    University of Gävle, Faculty of Education and Business Studies, Department of Culture Studies, Religious Studies and Educational Sciences, Religous studies.
    Janlert, Urban
    Umeå universitet.
    Hamberg, Katarina
    Umeå universitet.
    Forssén, Annika
    Umeå universitet.
    A cross-sectional and semantic investigation of self-rated health in the northern Sweden MONICA-study2012In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 12, p. 154-Article in journal (Refereed)
    Abstract [en]

    Background: Self-Rated Health (SRH) correlates with risk of illness and death. But how are different questions of SRH to be interpreted? Does it matter whether one asks: "How would you assess your general state of health?"(General SRH) or "How would you assess your general state of health compared to persons of your own age?"(Comparative SRH)? Does the context in a questionnaire affect the answers? The aim of this paper is to examine the meaning of two questions on self-rated health, the statistical distribution of the answers, and whether the context of the question in a questionnaire affects the answers. Methods: Statistical and semantic methodologies were used to analyse the answers of two different SRH questions in a cross-sectional survey, the MONICA-project of northern Sweden. Results: The answers from 3504 persons were analysed. The statistical distributions of answers differed. The most common answer to the General SRH was "good", while the most common answer to the Comparative SRH was "similar". The semantic analysis showed that what is assessed in SRH is not health in a medical and lexical sense but fields of association connected to health, for example health behaviour, functional ability, youth, looks, way of life. The meaning and function of the two questions differ - mainly due to the comparing reference in Comparative SRH. The context in the questionnaire may have affected the statistics. Conclusions: Health is primarily assessed in terms of its sense-relations (associations) and Comparative SRH and General SRH contain different information on SRH. Comparative SRH is semantically more distinct. The context of the questions in a questionnaire may affect the way self-rated health questions are answered. Comparative SRH should not be eliminated from use in questionnaires. Its usefulness in clinical encounters should be investigated.

  • 36.
    Waller, Göran
    et al.
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
    Thalén, Peder
    Department for Cultural Studies, Religious Studies and Educational Sciences, University of Gävle, Gävle, Sweden.
    Janlert, Urban
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Epidemiology and Global Health.
    Hamberg, Katarina
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
    Forssén, Annika
    Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Family Medicine.
    A cross-sectional and semantic investigation of self-rated health in the northern Sweden MONICA-study2012In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 12, article id 154Article in journal (Refereed)
    Abstract [en]

    Background: Self-Rated Health (SRH) correlates with risk of illness and death. But how are different questions of SRH to be interpreted? Does it matter whether one asks: “How would you assess your general state of health?”(General SRH) or “How would you assess your general state of health compared to persons of your own age?”(Comparative SRH)? Does the context in a questionnaire affect the answers? The aim of this paper is to examine the meaning of two questions on self-rated health, the statistical distribution of the answers, and whether the context of the question in a questionnaire affects the answers.

    Methods: Statistical and semantic methodologies were used to analyse the answers of two different SRH questions in a cross-sectional survey, the MONICA-project of northern Sweden.

    Results: The answers from 3504 persons were analysed. The statistical distributions of answers differed. The most common answer to the General SRH was “good”, while the most common answer to the Comparative SRH was “similar”. The semantic analysis showed that what is assessed in SRH is not health in a medical and lexical sense but fields of association connected to health, for example health behaviour, functional ability, youth, looks, way of life. The meaning and function of the two questions differ – mainly due to the comparing reference in Comparative SRH. The context in the questionnaire may have affected the statistics.

    Conclusions: Health is primarily assessed in terms of its sense-relations (associations) and Comparative SRH and General SRH contain different information on SRH. Comparative SRH is semantically more distinct. The context of the questions in a questionnaire may affect the way self-rated health questions are answered. Comparative SRH should not be eliminated from use in questionnaires. Its usefulness in clinical encounters should be investigated.

  • 37. Wettergren, Lena
    et al.
    Lindberg, Mathilde Hedlund
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Centre for Research Ethics and Bioethics.
    Kettis, Åsa
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Centre for Research Ethics and Bioethics.
    Glimelius, Bengt
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Radiology, Oncology and Radiation Science, Oncology.
    Ring, Lena
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Public Health and Caring Sciences, Centre for Research Ethics and Bioethics.
    Comparison of two instruments for measurement of quality of life in clinical practice - a qualitative study2014In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 14, p. 115-Article in journal (Refereed)
    Abstract [en]

    Background: The study aimed to investigate the meaning patients assign to two measures of quality of life: the Schedule for Evaluation of Individual Quality of Life Direct Weighting (SEIQoL-DW) and the SEIQoL-DW Disease Related (DR) version, in a clinical oncology setting. Even though the use of quality of life assessments has increased during the past decades, uncertainty regarding how to choose the most suitable measure remains. SEIQoL-DW versions assesses the individual's perception of his or her present quality of life by allowing the individual to nominate the domains to be evaluated followed by a weighting procedure resulting in qualitative (domains) as well as quantitative outcomes (index score). Methods: The study applied a cross-sectional design with a qualitative approach and collected data from a purposeful sample of 40 patients with gastrointestinal cancer. Patients were asked to complete two measures, SEIQoL-DW and the SEIQoL-DR, to assess quality of life. This included nomination of the areas in life considered most important and rating of these areas; after completion patients participated in cognitive interviews around their selections of areas. Interviews were audiotaped and transcribed verbatim which was followed by analysis using a phenomenographic approach. Results: The analyses of nominated areas of the two measures resulted in 11 domains reflecting what patients perceived had greatest impact on their quality of life. Analysis of the cognitive interviews resulted in 16 thematic categories explaining the nominated domains. How patients reflected around their quality of life appeared to differ by version (DW vs. DR). The DW version more often related to positive aspects in life while the DR version more often related to negative changes in life due to having cancer. Conclusions: The two SEIQoL versions tap into different concepts; health-related quality of life, addressing losses and problems related to having cancer and, quality of life, more associated with aspects perceived as positive in life. The SEIQoL-DR and the SEIQoL-DW are recommended in clinical practice to take both negative and positive aspects into account and acting on the problems of greatest importance to the patient.

  • 38.
    Wuytack, Francesca
    et al.
    Trinity Coll Dublin, Ireland.
    Gutke, Annelie
    Univ Gothenburg, Sweden.
    Stuge, Britt
    Oslo Univ Hosp, Norway.
    Morkved, Siv
    Norwegian Univ Sci and Technol, Norway.
    Olsson, Christina
    Morby Acad Primary Healthcare Ctr, Sweden.
    Robinson, Hilde Stendal
    Univ Oslo, Norway.
    Vollestad, Nina K.
    Univ Oslo, Norway.
    Öberg, Birgitta
    Linköping University, Department of Medical and Health Sciences, Division of Physiotherapy. Linköping University, Faculty of Medicine and Health Sciences.
    Wikmar, Lena Nilsson
    Karolinska Inst, Sweden.
    Saldana Mena, Juan Jose
    Univ Estatal Valle Ecatepec, Mexico.
    Smith, Valerie
    Trinity Coll Dublin, Ireland.
    Protocol for the development of a core outcome set for pelvic girdle pain, including methods for measuring the outcomes: the PGP-COS study2018In: BMC Medical Research Methodology, ISSN 1471-2288, E-ISSN 1471-2288, Vol. 18, article id 158Article in journal (Refereed)
    Abstract [en]

    BackgroundPelvic Girdle Pain (PGP) is an important cause of disability and economic cost worldwide. There is a need for effective preventative and management strategies. Emerging studies measure a variety of outcomes rendering synthesis and translation to clinical practice difficult. A Core Outcome Set (COS) can address this problem by ensuring that data are relevant, useful and usable for making well-informed healthcare choices. The aim of this study is to develop a consensus-based PGP-COS, including agreement on methods (e.g. instruments) for measuring the construct outcomes in the COS for use in research and clinical practice. Furthermore, as there is uncertainty as to whether incorporating stakeholder interviews in addition to conducting a systematic review to determine an initial list of outcomes for the Delphi survey, or, whether using different rating scales in a Delphi survey impacts on the final COS, we propose to embed two methodological studies within the PGP-COS development process to address these questions.MethodsThe PGP-COS study will include five phases: (1) A systematic review of the literature and semi-structured interviews with 15 patients (three countries) to form the initial list of outcomes for the Delphi survey; (2) A 3-round Delphi including patients, clinicians, researchers and service providers; (3) A systematic review of methods for measuring the outcomes in the preliminary PGP-COS identified in the Delphi survey; (4) A face-to-face consensus meeting to agree on the final PGP-COS and methods for measuring the COS; (5) Global dissemination.To address the methodological questions, we will assess the number and type of outcomes, in the final PGP-COS, that were exclusively derived from the interviews. Secondly, we will randomise Delphi survey participants to either a 5-point or 9-point importance rating scale, and examine potential differences in important ratings between the groups.DiscussionThere is currently no COS for measuring/monitoring PGP in trials and clinical practice. A PGP-COS will ensure that relevant outcomes are measured using appropriate measurement instruments for patients with PGP globally.Core outcome set registrationThis PGP-COS was registered with COMET (Core Outcome Measures for Effectiveness Trials) in January 2017 (http://www.comet-initiative.org/studies/details/958).

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