Self-rated health and symptomatic knee osteoarthritis over three years: data from a multicenter observational cohort study.

OBJECTIVE: To determine if a previously published model of the influence of self-rated health on physical, mental, and social health among patients with joint replacement surgery could be generalized to persons with symptomatic knee osteoarthritis (OA). Our second purpose was to determine if self-rated health mediated changes in physical, mental, and social health.
METHODS: Persons with symptomatic knee OA (n = 1,127) who participated in the Osteoarthritis Initiative study completed the required measures at baseline and at 1-, 2-, and 3-year intervals. The key variable of interest was a single-item self-rated health measure. In addition, measures of physical, mental, and social health and a set of covariate measures over the 3-year period were analyzed. Structural equation modeling was used to test interrelationships among variables, as well as predictive and mediational relationships among self-rated health and mental, physical, and social health after adjusting for baseline covariates.
RESULTS: The full model demonstrated good statistical fit. Prior self-rated health consistently predicted current mental health and social health. Prior social health predicted current self-rated health. Self-rated health also mediated changes in mental health and social health. Only social health changes were mediated by self-rated health over all time periods.
CONCLUSION: Self-rated health predicts a variety of outcomes of symptomatic knee OA. In addition, self-rated health mediates changes in social health and mental health. The use of self-rated health as a simple and efficient clinical assessment has potential for clinical utility because of its predictive capability and association with multiple health domains.