Comparing Medicare and Non-Medicare Inpatient Total Knee Arthroplasty: Is the New Centers for Medicare and Medicaid Services Patient-Reported Outcomes Performance Measure Mandate Applicable to All?

Background: The Centers for Medicare & Medicaid Services (CMS) has implemented the Patient-Reported Outcomes Performance Measure policy to assess the quality of total joint arthroplasty. However, the representativeness of this policy of the entire total knee arthroplasty (TKA) population remains uncertain. We aimed to compare characteristics, completion rates for the CMS-mandated variables, and achievement of substantial clinical benefit (SCB) threshold between inpatient Medicare and non-Medicare TKA patients. Methods: A prospective cohort of 4,301 primary inpatient TKAs between 2016 and 2022 from a single health care system was analyzed. The cohort was divided into Medicare (n = 2,812), Medicaid (n = 197), commercial (n = 1,232), workers’ compensation (n = 15), and self-paid (n = 45) groups. Demographics and 1-year Knee Injury and Osteoarthritis Outcome Score-Joint Replacement were compared between groups. The SCB for Knee Injury and Osteoarthritis Outcome Score-Joint Replacement was defined using the proposed threshold by CMS. Results: Medicare patients accounted for 65% of the total cohort, whereas commercial, Medicaid, self-paid, and workers’ compensation groups represented 29, 5, 1, and 0.3%, respectively. Medicare patients were older (median age 72, P < 0.001) with a higher proportion of patients who had a Charlson Comorbidity Index of ≥ 2 (40%, P < 0.001). Baseline patient-reported outcome measures (PROMs) capture rates were highest in the commercial group (93%), followed by self-paid (90%). At 1-year post-TKA, PROMs capture rates were highest in Medicare and commercial groups (77% each). Non-Medicare patients had higher odds of not achieving SCB-joint arthroplasty than Medicare patients (odds ratio = 1.3, P = 0.02). Conclusions: Medicare patients constituted two-thirds of inpatient TKA cases, were older, had more comorbidities, different PROMs capture rates, and higher odds of meeting CMS SCB-joint arthroplasty thresholds than non-Medicare groups. To improve the application of the new CMS policy, accounting for these disparities is essential. Level of Evidence: III.