Association Between Regional Social Vulnerability and Race-Based Differences in Total Knee Arthroplasty Use Among Medicare Beneficiaries

Background There is inequity in total knee arthroplasty (TKA) use between racial groups. The social vulnerability index (SVI) may characterize mechanisms underlying disparity, which is essential for identifying targeted interventions. We examined the relationship of the overall SVI and its themes with TKA use rates for Black and White Medicare beneficiaries and the difference in TKA utilization between these groups. Methods We used 2013-2017 Medicare data to calculate annual TKA use rates per 1000 beneficiaries in each hospital referral region (HRR). Multivariable mixed-effects linear regressions estimated the relationship between social vulnerability and TKA use. Results The mean (standard deviation) TKA rates were 9.4 (1.7) and 5.9 (2.2) per 1000 White and Black beneficiaries, respectively. HRRs with highest social vulnerability (quartile 4) had lower TKA rates for White (estimate for quartile 4: −1.7, 95% confidence interval [CI]: −2.2 to −1.1, P < .001) and Black beneficiaries (quartile 4: −1.7, 95% CI: −2.3 to −1.0, P < .001) compared to HRRs with the least vulnerability. The SVI's minority status and language theme was linked with wider rate differences between White and Black beneficiaries (quartile 4: 0.6, 95% CI: 0.0-1.2, P = .046). Conclusions Worse overall SVI was related to lower TKA use rates for both White and Black Medicare beneficiaries. Areas with the highest minority status and language vulnerability had disproportionately lower TKA rates for Black compared to White beneficiaries. Our findings suggest regional mechanisms that health-care professionals and policymakers will need to address to ensure equitable TKA access.