Confirmatory factor analysis of the validity of the SF-12 for persons with and without a history of stroke
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To assess the validity of the Physical and Mental Component Summary scores (PCS and MCS) of the 12-item Short-Form Health Survey (SF-12), a measure of health-related quality of life (HRQoL), among persons with a history of stroke.
Persons with (n = 2,581) and without (n = 38,066) a reported history of stroke were enrolled in the REasons for Geographic And Racial Differences in Stroke (REGARDS) study. Confirmatory factor analysis methods were used to evaluate the fit of a 2-factor model that underlies the PCS and MCS and to examine the equivalence of the factors across both study groups.
The 2-factor model provided good fit to the data among individuals with and those without a self-reported history of stroke. Item factor loadings were found to be largely invariant across both groups, and correlational analyses confirmed that the two latent factors were highly related to the PCS and MCS scores, calculated by the standard scoring algorithms. The effect of stroke history on physical health was more than twice its effect on mental health.
The psychometric measurement model that underlies the PCS and MCS summary scores is comparable between persons with and without a history of stroke. This suggests that the SF-12 has adequate validity for measuring HRQoL not only in the general population but also in cohorts following stroke.
KeywordsStroke SF-12 Psychometrics Confirmatory factor analysis Factor invariance
This research project is supported by a cooperative agreement U01 NS041588 from the National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Department of Health and Human Service. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NINDS or the National Institutes of Health. Representatives of the funding agency have been involved in the review of the manuscript but not directly involved in the collection, management, analysis, or interpretation of the data. The authors thank the other investigators, the staff, and the participants of the REGARDS study for their valuable contributions. A full list of participating REGARDS investigators and institutions can be found at http://www.regardsstudy.org Additional funding was provided by an investigator-initiated grant from NINDS (R01 NS045789, David L. Roth, PI). Representatives from the NINDS did not have any role in the design and conduct of the study, the collection, management, analysis, and interpretation of the data, or the preparation or approval of the manuscript.
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