Objective To determine whether there are racial differences in social support among patients with knee osteoarthritis (OA) and whether the impact of social support on patient preferences for total knee replacement (TKR) varies by race and sex. Methods A total of 514 white and 285 African American patients with knee OA were surveyed. Logistic regression models were performed to determine if the relationship between willingness to undergo TKR and the interaction of patient race and sex was mediated by social support. Results Compared to whites with knee OA, African American patients were less likely to be married (P < 0.001), reported less close friends/relatives (P < 0.001), and had lower Medical Outcomes Study Social Support Scale (MOS-SSS) scores (P < 0.001). African American patients were also less willing to undergo TKR (62% versus 80%; P < 0.001) than whites. The odds of willingness to undergo TKR were less in white females compared to white males when adjusted for recruitment site, age, income, and the Western Ontario and McMaster Universities Osteoarthritis Index score (odds ratio [OR] 0.57, 95% confidence interval [95% CI] 0.34-0.96). This difference was no longer significant when further adjusted for marital status, number of close friends/relatives, and MOS-SSS score, but the effect size remained unchanged (OR 0.60, 95% CI 0.35-1.02). The odds of willingness to undergo TKR remained much less in African American females (OR 0.35, 95% CI 0.19-0.64) and African American males (OR 0.28, 95% CI 0.14-0.54) compared to white males when controlled for sociodemographic, clinical, and social support measures. Conclusion African American patients reported less structural and functional social support than whites. Social support is an important determinant of preference for TKR surgery only among whites.
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