Dually Insured Medicare/Medicaid Patients Undergoing Primary TJA Have More Comorbidities, Higher Complication Rates, and Lower Reimbursements Compared to Privately Insured Patients

Background: Dual eligibility status (DES: qualifying for both Medicare and a Medicaid supplement) was recently proposed by the Center for Medicare and Medicaid Services as a socioeconomic qualifier for risk adjustment in primary total joint arthroplasty. However, the profile and outcomes of DES patients have never been compared to privately insured patients.

Methods: A retrospective case-control study of the Mariner database within the PearlDiver server between 2010 and 2017 was performed. Patients aged 60 to 80 undergoing primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) (separately) were stratified based upon payer type: DES versus private payer. A propensity score-matched analysis with nearest neighbor pairing (1:1 ratio) was performed to compare 90-day outcomes and reimbursements.

Results: A total of 315,664 private and 3961 DES THA patients and 670,899 private and 2255 DES TKA patients were identified. DES patients were older and had a greater prevalence of comorbidities (31/36, P < .001). The THA DES matched cohort had greater transfusion rates (6.8% versus 3.9%, P < .001), higher 90-day emergency department visits (22.8% versus 16.3%, P < .001) and readmissions (16.8% versus 9.5%, P < .001), and lower reimbursements ($19,615 versus $13,036, P < .001). The TKA DES matched cohort had more cardiac events (0.4% versus 0.09%, P = .03), emergency department visits (25.2% versus 19.9%, P < .001), readmissions (14.4% versus 11.2%, P = .001), and reoperations (0.85% versus 0.35%, P = .03) CONCLUSION: DES patients have different comorbidity profiles, and even after propensity score matching have a greater risk of complications and are reimbursed less compared to privately insured patients. In the setting of alternative payment models, these differences should be accounted for through risk adjustment.