Geographic Variation and Disparities in Total Joint Replacement Use for Medicare Beneficiaries: 2009 to 2017
Authors: Thirukumaran Caroline P. , Cai Xueya , Glance Laurent G. , Kim Yeunkyung , Ricciardi Benjamin F. , Fiscella Kevin A. , Li Yue 
Published: October 2020

Background:
Little is known about how the geographic variation and disparities in use of elective primary total hip and knee replacements for Medicare beneficiaries have evolved in recent years. The study objectives are to determine these variations and disparities, whether Black Medicare beneficiaries have continued to undergo fewer total hip replacements and total knee replacements across regions, and whether disparities affected all Black beneficiaries or mainly affected socioeconomically disadvantaged Black beneficiaries.

Methods:
We used 2009 to 2017 Medicare enrollment and claims data to examine Hospital Referral Region (HRR)-level variation and disparities by race (non-Hispanic White and Black) and socioeconomic status (Medicare-only and dual eligibility for both Medicare and Medicaid). The outcomes were HRR-level age and sex-standardized total hip replacement and total knee replacement utilization rates for White Medicare-only beneficiaries, White dual-eligible beneficiaries, Black Medicare-only beneficiaries, and Black dual-eligible beneficiaries, and the differences in rates between these groups as a representation of disparities. The key exposure variables were race-socioeconomic group and year. We constructed multilevel mixed-effects linear regression models to estimate trends in total hip replacement and total knee replacement rates and to examine whether rates were lower in HRRs with high percentages of Black beneficiaries or dual-eligible beneficiaries.

Results:
The study included 924,844 total hip replacements and 2,075,968 total knee replacements. In 2017, the mean HRR-level total hip replacement rate was 4.64 surgical procedures per 1,000 beneficiaries, and the mean HRR-level total knee replacement rate was 9.66 surgical procedures per 1,000 beneficiaries, with a threefold variation across HRRs. In 2017, the total hip replacement rate was 32% higher for White Medicare-only beneficiaries and 48% higher for Black Medicare-only beneficiaries than in 2009 (p < 0.001). However, because the surgical rates for White and Black dual-eligible beneficiaries remained unchanged over the study period, the 2017 Medicare-only and dual-eligible disparity for White beneficiaries increased by 0.75 surgical procedures per 1,000 from 2009 (40.98% increase; p = 0.03), and the disparity for Black beneficiaries by 1.13 surgical procedures per 1,000 beneficiaries (297.37% increase; p < 0.001). The total knee replacement disparities remained unchanged. Notably, the rates for White dual-eligible beneficiaries were significantly lower than those for Black Medicare-only beneficiaries (p < 0.001 for both total hip replacements and total knee replacements), and fewer surgical procedures were conducted in HRRs with a higher density of Black or dual-eligible beneficiaries.

Conclusions:
Although the total hip replacement use for Medicare-only beneficiaries of both races increased, disparities for White and Black dual-eligible beneficiaries (compared with their Medicare-only counterparts) are increasing. Efforts to improve equity must identify and address both racial and socioeconomic barriers and focus on regions with high concentrations of disadvantaged beneficiaries.

Clinical Relevance:
Although total hip replacements and total knee replacements are highly successful surgical procedures for end-stage osteoarthritis, our findings show that, as recently as 2017, Black beneficiaries and those dual eligible for Medicaid (a proxy for socioeconomic status) are less likely to undergo these surgical procedures and that there is profound geographic variation in the use of these surgical procedures. This evidence is essential for the design and implementation of disparity-reduction strategies focused on patients, providers, and geographic areas that can potentially improve the equity in joint replacement care.