Association of Geographic Social Vulnerability with Race-Based Differences in the Utilization of Total Hip Arthroplasty Surgeries for Medicare Beneficiaries.

Background: Racial disparities exist in the utilization of total hip arthroplasties (THAs). The social vulnerability index (SVI), which measures geographic-level disadvantage and includes themes such as socioeconomic status, minority status, and language, may partially explain disparities in THA use. Our objectives were to determine the association of the composite SVI with THA use for (i) White Medicare beneficiaries, (ii) Black Medicare beneficiaries, and (iii) the difference in THA use between White and Black beneficiaries. We also determined the association of SVI themes with these THA-use endpoints.

Methods: We used 2013 to 2019 Medicare data to calculate age- and sex-standardized THA use rates for 306 Hospital Referral Regions (HRRs). We estimated multivariable linear regression models to determine the association of the composite SVI and its four themes with THA utilization and with differences in use rates.

Results: Living in HRRs with the highest SVI (most vulnerable, quartile 4) was associated with lower hip arthroplasty rates for both White and Black beneficiaries (e.g., quartile 4 for White beneficiaries: -0.9, 95% confidence interval [95% CI]: -1.2 to -0.7, P < 0.001; quartile 4 for Black beneficiaries: -0.9, 95% CI: -1.3 to -0.5, P < 0.001) compared to beneficiaries in the least vulnerable HRRs (quartile 1). Higher vulnerability in minority status and language (theme 3) was associated with lower THA utilization for Black beneficiaries only (e.g., quartile 4 for Black beneficiaries: -0.9, 95% CI: -1.2 to -0.5, P < 0.001) and was associated with widening of the White-Black difference in THA utilization (e.g., quartile 4: 0.7, 95% CI: 0.3 to 1.1, P < 0.001).

Conclusion: Higher composite SVI is associated with lower THA utilization for both White and Black beneficiaries. Higher vulnerability in minority status and language is associated with the widening of the disparity in THA rates. Our findings highlight important mechanisms that need to be addressed to ensure equity in THA access.