Socioeconomic Risk Adjustment Models for Reimbursement Are Necessary in Primary Total Joint Arthroplasty

Abstract

Background: Alternative payment models, such as bundled payments, aim to control rising costs for total knee arthroplasty (TKA) and total hip arthroplasty (THA). Without risk adjustment for patients who may utilize more resources, concerns exist about patient selection and access to care. The purpose of this study was to determine whether lower socioeconomic status (SES) was associated with increased resource utilization following TKA and THA.

Methods: Using the Michigan Arthroplasty Registry Collaborative Quality Initiative database, we reviewed a consecutive series of 4168 primary TKA and THA patients over a 3-year period. We defined lowest SES based upon the median household income of the patient's ZIP code. Demographics, medical comorbidities, length of stay, discharge destination, and readmission rates were compared between patients of lowest SES and higher SES.

Results: Patients in the lowest SES group had a longer hospital length of stay (2.79 vs 2.22 days, P < .001), were more likely to be discharged to a rehabilitation facility (27% vs 18%, P < .001), and be readmitted to the hospital within 90 days (11% vs 8%, P = .002) than the higher SES group. Multivariate analysis revealed that lowest SES was an independent risk factor for all 3 outcome variables (all P < .001).

Conclusion: Patients in the lowest SES group utilize more resources in the 90-day postoperative period. Therefore, risk adjustment models, including SES, may be necessary to fairly compensate hospitals and surgeons and to avoid potential problems with access to joint arthroplasty care.

Keywords: alternative payment models; readmission; risk adjustment; socioeconomic status; total hip arthroplasty; total knee arthroplasty.