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Data quality in the National Prostate Cancer Register (NPCR) of Sweden
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Urology and Andrology.
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Data in quality registers are increasingly used for quality assurance of health care, benchmarking, and research. If valid conclusions are to be drawn from such studies, it is vital that register data have high quality. The aim of this thesis was to assess data quality in the National Prostate Cancer Register (NPCR) of Sweden, a nationwide register that since 1998 captures 98% of all cases of Prostate cancer (Pca) in Sweden. The proportion and characteristics of Pca cases not registered in NPCR was investigated in paper I. Four dimensions of data quality were evaluated for NPCR in paper II: completeness, timeliness, comparability, and validity. Proportion and characteristics of Pca cases registered in NPCR but with unknown risk category were investigated in paper III. Finally, the association between Socioeconomic Status (SES) and Pca diagnosis, treatment, and mortality was studied in paper IV. 

Material and methods: Data quality of NPCR was studied by cross-linkages between NPCR and other health care registers and demographical databases by use of the Swedish personal identity number. Validity was further studied by re-abstraction of patient health care records, followed by comparison of re-abstracted and original register data.

Results: Men not registered in NPCR, who constituted around 2% of all cases in the Swedish Cancer Register, differed only modestly in characteristics from cases in NPCR, indicating that NPCR is generalizable for all men with Pca in Sweden. Data quality in NPCR was high overall, with high completeness compared to the Swedish Cancer Register with registration mandated by law and few Pca cases were detected by use of death certificates. There was timely registration, and good comparability with registration forms and coding routines that were compliant with international guidelines. Data validity was high with high agreement and correlation for key variables. Men with unknown risk category had, compared to men with known risk category, more often concomitant bladder cancer, higher comorbidity, and lower Pca mortality. Men with high SES had, compared to men with low SES, higher probability of Pca detected during health checkup, shorter waiting times for prostatectomy, and higher probability of curative treatment for intermediate and high-risk cancer. Pca mortality was lower in men with high SES than in men with low SES for high-risk cancer.

Conclusion: These results indicate that data quality in NPCR is high and that NPCR is population-based. There were consistent differences in diagnostic and therapeutic activity according to SES despite an equal access tax-financed healthcare system in Sweden. 

Place, publisher, year, edition, pages
Umeå: Umeå University , 2018. , p. 44
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1945
Keywords [en]
Prostate cancer, Cancer quality register, Data quality, Evaluation, Validity
National Category
Urology and Nephrology
Identifiers
URN: urn:nbn:se:umu:diva-144553ISBN: 978-91-7601-831-6 (print)OAI: oai:DiVA.org:umu-144553DiVA, id: diva2:1180609
Public defence
2018-03-02, E04, Farmakologihuset, Norrlands Universitetssjukhus, Umeå, 09:00 (Swedish)
Opponent
Supervisors
Funder
Swedish Research Council, 2012-5047Swedish Cancer Society, 2016-0700Available from: 2018-02-09 Created: 2018-02-06 Last updated: 2018-06-09Bibliographically approved
List of papers
1. Capture rate and representativity of The National Prostate Cancer Register of Sweden
Open this publication in new window or tab >>Capture rate and representativity of The National Prostate Cancer Register of Sweden
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2015 (English)In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 54, no 2, p. 158-163Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Capture rate and representativity of quality registers need to be assessed in order to ensure that register data are generalizable. MATERIAL AND METHODS: In 1998-2009, 103 047 men had been diagnosed with prostate cancer and registered in the Swedish Cancer Register to which registration is mandated by law and of these men, 100 849 men (98%) had also been registered in The National Prostate Cancer Register (NPCR) of Sweden. We compared demographics, cancer treatment, comorbidity, and mortality in men in NPCR, with those who had only been registered in the Cancer Register, by use of data from the Cause of Death Register, the In-Patient Register and the Prescribed Drug Register. In addition, we identified 1929 men who had prostate cancer as underlying cause of death in the Cause of Death Register who had neither been registered in the Cancer Register nor in NPCR. RESULTS: Compared to men in NPCR, men only registered in the Cancer Register were slightly older, median age 72 versus 71 years, and a lower proportion underwent radical prostatectomy, 15% versus 27%. Ten year prostate cancer mortality was 23% (95% CI 20-25) for men in the Cancer Register only and 24% (95% CI 24-25) in NPCR, while mortality from competing causes was 28% (95% CI 26-31) and 30% (95% CI 30-30), respectively. Men identified with prostate cancer by a death certificate were old and had high comorbidity. CONCLUSION: The capture rate of NPCR is very high and there are only modest differences in demographics, cancer treatment, comorbidity, and mortality between the small proportion of men only registered in the Cancer Register and men registered in NPCR, indicating that information in NPCR can be generalized to all men with prostate cancer in Sweden.

Place, publisher, year, edition, pages
Informa Healthcare, 2015
Keywords
prostatic neoplasm, quality register, Cancer Register, Cause of Death Register
National Category
Cancer and Oncology
Identifiers
urn:nbn:se:umu:diva-94131 (URN)10.3109/0284186X.2014.939299 (DOI)000348301400003 ()25034349 (PubMedID)
Available from: 2014-10-05 Created: 2014-10-05 Last updated: 2018-06-07Bibliographically approved
2. Evaluation of data quality in the National Prostate Cancer Register of Sweden
Open this publication in new window or tab >>Evaluation of data quality in the National Prostate Cancer Register of Sweden
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2015 (English)In: European Journal of Cancer, ISSN 0959-8049, E-ISSN 1879-0852, Vol. 51, no 1, p. 101-111Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Data in cancer quality registers are increasingly used for quality assurance, benchmarking, and research. 

MATERIALS AND METHODS: Data in the National Prostate Cancer Register (NPCR) of Sweden were evaluated for completeness, timeliness, comparability and validity. Completeness and timeliness were assessed by cross-linkage to the Swedish Cancer Register, comparability was examined by comparing registration routines in NPCR with national and international guidelines, and validity was assessed by re-abstraction of data from medical charts for 731 men diagnosed with prostate cancer (Pca) in 2009. Furthermore, data on treatment were validated by record linkage to the Swedish Patient Register and The Prescribed Drug Register. 

RESULTS: NPCR captured 98% of Pca cases in the Cancer Register and the mean value for completeness of the 48 evaluated variables was 90% (range 64-100%). Timeliness increased substantially from 2008 to 2012 with 95% of cases reported within 12months after diagnosis in 2012. NPCR complied with national and international coding routines. Overall, the agreement between original data and re-abstracted data from 731 charts was high. For example, the correlation between original and re-abstracted data was 1.00 for date of surgery, and 0.97 for serum levels of prostate specific antigen and exact agreement was 97% for Gleason score at biopsy, 83% for clinical local T stage and more than 95% of the androgen deprivation therapies registered in NPCR had a corresponding filled prescription. 

CONCLUSION: Record linkages with other data sources and re-abstraction of data showed that data quality in NPCR is high.

Keywords
Prostate cancer, Cancer quality register, Evaluation, Validity
National Category
Clinical Medicine
Identifiers
urn:nbn:se:umu:diva-97301 (URN)10.1016/j.ejca.2014.10.025 (DOI)000346740300012 ()25465187 (PubMedID)
Available from: 2014-12-13 Created: 2014-12-13 Last updated: 2018-06-07Bibliographically approved
3. Proportion and characteristics of men with unknown risk category in the National Prostate Cancer Register of Sweden
Open this publication in new window or tab >>Proportion and characteristics of men with unknown risk category in the National Prostate Cancer Register of Sweden
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2016 (English)In: Acta Oncologica, ISSN 0284-186X, E-ISSN 1651-226X, Vol. 55, no 12, p. 1461-1466Article in journal (Refereed) Published
Abstract [en]

Introduction: Knowledge on missing data in a clinical cancer register is important to assess the validity of research results. For analysis of prostate cancer (Pca), risk category, a composite variable based on serum levels of prostate specific antigen (PSA), stage, and Gleason score, is crucial for treatment decisions and a strong determinant of outcome. The aim of this study was to assess the proportion and characteristics of men in the National Prostate Cancer Register (NPCR) of Sweden with unknown risk category.

Material and methods: Men diagnosed with prostate cancer between 1998 and 2012 registered in NPCR with known or unknown risk category were compared with respect to age, socioeconomic factors, comorbidity, cancer characteristics, cancer treatment, and mortality from Pca and other causes.

Results: In total, 3 315 out of 129 391 (3%) men had unknown risk category. Compared to other men in NPCR, these men more often had a concomitant bladder cancer diagnosis, 19% vs. 1%, diagnosis of benign prostatic hyperplasia 31% vs. 5%, received unspecified Pca cancer treatment 16% vs. 3%, had higher comorbidity, Charlson Comorbidity Index 2 or higher, 34% vs. 13%, and had lower Pca mortality 12% vs. 30%, but similar mortality from other causes.

Conclusion: Men with unknown risk category were rare in NPCR but distinctly different from other men in many aspects in particular regarding comorbidity and Pca mortality.

Place, publisher, year, edition, pages
Taylor & Francis, 2016
Keywords
prostate cancer, clinical cancer register, risk classification, missing data
National Category
Urology and Nephrology Cancer and Oncology
Research subject
Medicine
Identifiers
urn:nbn:se:umu:diva-127328 (URN)10.1080/0284186X.2016.1234716 (DOI)000389182700013 ()27749139 (PubMedID)
Funder
Swedish Research Council, 2012-5047Swedish Cancer Society, 140570
Available from: 2016-11-07 Created: 2016-11-07 Last updated: 2018-06-09Bibliographically approved
4. Socioeconomic status and diagnosis, treatment, and mortality in men with prostate cancer. Nationwide population-based study
Open this publication in new window or tab >>Socioeconomic status and diagnosis, treatment, and mortality in men with prostate cancer. Nationwide population-based study
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2018 (English)In: International Journal of Cancer, ISSN 0020-7136, E-ISSN 1097-0215Article in journal (Refereed) Epub ahead of print
Abstract [en]

Patients with high socioeconomic status (SES) have better cancer outcomes than patients with low SES. This has also been shown in Sweden, a country with tax-financed health care aiming to provide care on equal terms to all residents. The association between income and educational level and diagnostics and treatment as outlined in national guidelines and prostate cancer (Pca) and all-cause mortality was assessed in 74,643 men by use of data in the National Prostate Cancer Register of Sweden and a number of other health care registers and demographic databases. In multivariable logistic regression analysis, men with high income had higher probability of Pca detected in a health-check-up, top versus bottom income quartile, odds ratio (OR) 1.60 (95% CI 1.45-1.77) and lower probability of waiting more than 3 months for prostatectomy, OR 0.77 (0.69-0.86). Men with the highest incomes also had higher probability of curative treatment for intermediate and high-risk cancer, OR 1.77 (1.61-1.95) and lower risk of positive margins, (incomplete resection) at prostatectomy, OR 0.80 (0.71-0.90). Similar, but weaker associations were observed for educational level. At 6 years of follow-up, Pca mortality was modestly lower for men with high income, which was statistically significant for localized high-risk and metastatic Pca in men with no comorbidities. All-cause mortality was less than half in top versus bottom quartile of income (12% vs. 30%, p < 0.001) among men above age 65. Our findings underscore the importance of adherence to guidelines to ensure optimal and equal care for all patients diagnosed with cancer.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
clinical cancer register, prostate cancer, socioeconomic status
National Category
Urology and Nephrology
Research subject
Cancer Epidemiology
Identifiers
urn:nbn:se:umu:diva-144548 (URN)10.1002/ijc.31272 (DOI)29363113 (PubMedID)
Funder
Swedish Research Council, 2012-5047Swedish Cancer Society, 2016-0700
Available from: 2018-02-06 Created: 2018-02-06 Last updated: 2018-06-09Bibliographically approved

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