Alternative population sampling frames produced important differences in estimates of association: a case-control study of vasculitis

Gary J Macfarlane, Gareth T Jones, Leyla Swafe, David M Reid, Neil Basu

Research output: Contribution to journalArticle

Abstract

OBJECTIVE: A common population sampling frame in countries with universal health care is health service registers. We have evaluated the use of such a register, in the United Kingdom, against a commercially available database claiming large population coverage, an alternative that offers ease of access and flexibility of use. STUDY DESIGN AND SETTING: A case-control study of vasculitis, which recruited cases from secondary care clinics in Scotland, compared two alternative sampling frames for population controls, namely the registers of National Health Service (NHS) primary care practices and a commercially available database. The characteristics of controls recruited from both sources were compared in addition to separate case-control comparison using logistic regression. RESULTS: A total of 166 of 189 cases participated (88% participation rate), while both the commercial database and NHS Central Register (NHSCR) controls achieved a participation rate of 24% among persons assumed to have received the invitation. On several measures, the NHSCR patients reported poorer health than the commercial database controls: low scores on the physical component score of the Short Form 36 (odds ratio [OR]: 2.3; 95% confidence interval [CI]: 1.3-4.1), chronic widespread pain (OR: 2.3; CI: 1.1-4.7), and high levels of fatigue (OR: 2.0; CI: 1.3-3.1). These had an important influence on the estimates of association with case status with one association (pain) showing a strong and significant association using commercial database controls, which was absent with NHSCR controls. CONCLUSION: There are important differences in self-reported measures of health and quality of life using controls from two alternative population sampling frames. It emphasizes the importance of methodological rigor and prior assessment in choosing sampling frames for case-control studies.
Original languageEnglish
Pages (from-to)675-680
Number of pages6
JournalJournal of Clinical Epidemiology
Volume66
Issue number6
Early online date10 Jan 2013
DOIs
Publication statusPublished - Jun 2013

Fingerprint

Vasculitis
Case-Control Studies
Databases
Population
Odds Ratio
National Health Programs
Confidence Intervals
Secondary Care
Population Control
Health
Scotland
Chronic Pain
Health Services
Fatigue
Primary Health Care
Logistic Models
Quality of Life
Delivery of Health Care
Pain

Keywords

  • sampling frame
  • participation
  • case-control
  • odds ratios
  • health registers
  • vasculitis
  • bias

Cite this

Alternative population sampling frames produced important differences in estimates of association : a case-control study of vasculitis. / Macfarlane, Gary J; Jones, Gareth T; Swafe, Leyla; Reid, David M; Basu, Neil.

In: Journal of Clinical Epidemiology, Vol. 66, No. 6, 06.2013, p. 675-680.

Research output: Contribution to journalArticle

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AU - Jones, Gareth T

AU - Swafe, Leyla

AU - Reid, David M

AU - Basu, Neil

N1 - Copyright © 2012 Elsevier Inc. All rights reserved.

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N2 - OBJECTIVE: A common population sampling frame in countries with universal health care is health service registers. We have evaluated the use of such a register, in the United Kingdom, against a commercially available database claiming large population coverage, an alternative that offers ease of access and flexibility of use. STUDY DESIGN AND SETTING: A case-control study of vasculitis, which recruited cases from secondary care clinics in Scotland, compared two alternative sampling frames for population controls, namely the registers of National Health Service (NHS) primary care practices and a commercially available database. The characteristics of controls recruited from both sources were compared in addition to separate case-control comparison using logistic regression. RESULTS: A total of 166 of 189 cases participated (88% participation rate), while both the commercial database and NHS Central Register (NHSCR) controls achieved a participation rate of 24% among persons assumed to have received the invitation. On several measures, the NHSCR patients reported poorer health than the commercial database controls: low scores on the physical component score of the Short Form 36 (odds ratio [OR]: 2.3; 95% confidence interval [CI]: 1.3-4.1), chronic widespread pain (OR: 2.3; CI: 1.1-4.7), and high levels of fatigue (OR: 2.0; CI: 1.3-3.1). These had an important influence on the estimates of association with case status with one association (pain) showing a strong and significant association using commercial database controls, which was absent with NHSCR controls. CONCLUSION: There are important differences in self-reported measures of health and quality of life using controls from two alternative population sampling frames. It emphasizes the importance of methodological rigor and prior assessment in choosing sampling frames for case-control studies.

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