Two-State Comparison of Total Joint Arthroplasty Utilization Following Medicaid Expansion

Background

Although Medicaid expansion has improved access to primary care services, its impact on surgical specialty utilization remains unclear. The aim of this study is to determine whether Medicaid expansion is associated with increased utilization rates of total hip arthroplasty (THA) and total knee arthroplasty (TKA) in Illinois (which expanded Medicaid) relative to Missouri (which did not expand Medicaid).

Methods

Using administrative data sources, we analyzed 374,877 total hospitalizations (236,333 in Illinois and 138,544 in Missouri) for THA/TKA from 2011 to 2016 (Illinois’ Medicaid expansion date: January 1, 2014).

Results

The percentage of THA/TKA funded by Medicaid in Illinois was 2.4% in 2013 and 3.9% in 2016 (Missouri 2013: 2.7%; 2016: 2.6%). A difference-in-difference analysis (adjusted for patient age and gender, county-level Area Deprivation Index, and number of orthopedic surgeons) demonstrated a statistically significant increase in Medicaid-funded THA/TKA in Illinois in 2016 compared to 2013 (P = .012).

Conclusion

Our study demonstrates that Medicaid expansion in Illinois was associated with increased utilization of THA and TKA. Further study is needed to understand the impact of Medicaid expansion in other states and for other procedures.