Concentrated Economic Disadvantage Predicts Resource Utilization After Total Knee Arthroplasty

The Index of Concentration at the Extremes (ICE), a measure of geographic socioeconomic polarization, predicts several health outcomes but has not been evaluated concerning total knee arthroplasty (TKA). This study evaluates ICE as a predictor of post-TKA resource utilization.

Using the Healthcare Cost and Utilization Project's New York State database from 2016 to 2017, we retrospectively evaluated 57,426 patients ≥50 years undergoing primary TKA. The ICE values for extreme concentrations of income and race were calculated using United States Census Bureau data with the formula ICE_i = (P_i-D_i)/T_i where P_i, D_i, and T_i are the number of households in the most privileged extreme, disadvantaged extreme, and total population in zip code i, respectively. Extremes of privilege and disadvantage were defined as ≥$150,000 versus <$25,000 for income and non-Hispanic White versus non-Hispanic Black for race. Association of ICE values, demographics, and comorbidities with 90-day readmission and 90-day emergency department (ED) visits was examined using multivariable analysis.

Overall 90-day readmission and ED visit rates were 12.8% and 9.4%, respectively. On multivariable analysis, the lowest ICE_Income quintile (concentrated poverty) predicted 90-day readmission (odds ratio 1.17, 95% confidence interval 1.05 to 1.30, P = .005) and 90-day ED visit (odds ratio 1.22, 95% confidence interval 1.08 to 1.38, P = .001). The ICE_Race was not predictive of either outcome.

Patients in communities with the lowest ICE_Income values use more inpatient and ED resources after primary TKA. Incorporating ICE_Income into risk-adjusted payment models may help align incentives for equitable care.