Impact of Mean Family Income on Cumulative Incidence of Revision After Total Knee Arthroplasty.

Abstract

Socioeconomic inequality and mean family income are important predictors of adverse health outcomes, but few studies to date have examined their role in patients undergoing total knee arthroplasty (TKA). Our study assessed whether mean family income is associated with differing incidence of revision after TKA. A national all-payer claims database was used to evaluate primary TKAs between 2010 and 2022. Patients were stratified based on their zip-code-derived mean family incomes into five quintiles using income distribution data from the American Community Survey. Kaplan-Meier survival analysis was applied to these cohorts to determine two-year cumulative incidence of revision and corresponding hazard ratios (HR). In 816,319 patients undergoing TKA, the cumulative incidence of revision after two years for the 1^st (lowest) to 5^th (highest) income quintiles was 2.3, 2.2, 2.1, 2.1, and 1.9%, respectively. The risk of revision was highest for the 1^st income quintile (HR: 1.17; 95% confidence interval (CI): 1.09 to 1.25; P < 0.0001) and decreased until it was lowest for the 5^th income quintile (HR: 0.84; 95% CI: 0.81 to 0.87; P < 0.0001) when compared to the entire population. Revision for periprosthetic joint infection (1^st: HR: 1.14; 95% CI: 1.01 to 1.28; P = 0.038 versus 5th: HR: 0.87; 95% CI: 0.82 to 0.93; P < 0.0001), mechanical failure (1^st: HR: 1.16; 95% CI: 1.06 to 1.28; P = 0.002 versus 5^t^h: HR: 0.87; 95% CI: 0.83 to 0.92; P < 0.0001) and periprosthetic fracture (1^st: HR: 1.31; 95% CI: 1.21 to 1.42; P < 0.0001 versus 5^th: HR: 0.79; 95% CI: 0.75 to 0.83; P < 0.0001) revealed similar trends. Our results suggest that lower income quintiles are associated with increased risk of revision up to two years after TKA surgery. The observed inverse correlation between income levels and risk of revision underscores the need for more research and targeted interventions in this area.