Abstract
Introduction
Alternative payment models, such as bundled payments, aim to control rising costs for total knee (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 (MARCQI) database, we reviewed a consecutive series of 4,168 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. An a prioripower analysis was performed to determine the appropriate sample size. 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<0.001), were more likely to be discharged to a rehabilitation facility (27% vs. 18%, p<0.001), and be readmitted to the hospital within 90 days (11% vs. 8%, p=0.002) than the higher SES group. In the multivariate analysis, lowest SES was found to be an independent risk factor for 90-day readmission rate (OR 1.50, 95% CI 1.15–1.96, p=0.003), extended hospital LOS 4 days or greater (OR 2.34, 95% CI 1.78–3.07, p<0.001), and discharge to a rehabilitation facility (OR 1.64, 95% CI 1.34–2.01, p<0.001). Both age greater than 75 years and obesity were also independent risk factors for all three outcome measures.
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 replacement care.
