Open Access Short report

Measurement equivalence of the SF-36 in the canadian multicentre osteoporosis study

Lisa M Lix1*, Beliz Acan Osman2, Jonathan D Adachi3, Tanveer Towheed4, Wilma Hopman4, K Shawn Davison5 and William D Leslie6

Author Affiliations

1 School of Public Health, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada

2 Health Quality Council, 111 Research Drive, Saskatoon, SK, Canada

3 Faculty of Health Sciences, McMaster University, 1280 Main St. W, Hamilton, ON, Canada

4 Department of Community Health and Epidemiology, Carruthers Hall, Queen's University, Kingston, ON, Canada

5 College of Kinesiology, University of Saskatchewan, 87 Campus Drive, Saskatoon, Canada

6 Department of Internal Medicine, University of Manitoba, St. Boniface General Hospital, 409 Tache Avenue, Winnipeg, MB, Canada

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Health and Quality of Life Outcomes 2012, 10:29  doi:10.1186/1477-7525-10-29

Published: 13 March 2012

Abstract

Background

Studies that compare health-related quality of life (HRQOL) and other patient-reported outcomes in different populations rest on the assumption that the measure has equivalent psychometric properties across groups. This study examined the measurement equivalence (ME) of the 36-item Medical Outcomes Study Short Form Survey (SF-36), a widely-used measure of HRQOL, by sex and race in a population-based Canadian sample.

Findings

SF-36 data were from the Canadian Multicentre Osteoporosis Study, a prospective cohort study that randomly sampled adult men and women from nine sites across Canada. Confirmatory factor analysis (CFA) techniques were used to test hypotheses about four forms of ME, which are based on equality of the factor loadings, variances, covariances, and intercepts. Analyses were conducted for Caucasian and non-Caucasian females (n = 6,539) and males (n = 2,884). CFA results revealed that a measurement model with physical and mental health factors provided a good fit to the data. All forms of ME were satisfied for the study groups.

Conclusions

The results suggest that sex and race do not influence the conceptualization of a general measure of HRQOL in the Canadian population.

Keywords:
SF-36; Health-related quality of life; Psychometrics; Equivalence; Confirmatory factor analysis