Post-Discharge care duration, charges, and outcomes among medicare patients after primary total hip and knee arthroplasty

Background: In April 2016, the U.S. Centers for Medicare &Medicaid Services initiated mandatory 90-day bundled payments for total hip and knee arthroplasty for much of the country. Our goal was to determine duration of care, 90-day charges, and readmission rates by discharge disposition and U.S. region after hip or knee arthroplasty. Methods: Using the 2008 Medicare Provider Analysis and Review database 100% sample, we identified patients who had undergone elective primary total hip or knee arthroplasty. We collected data on patient age, sex, comorbidities, U.S. Census region, discharge disposition, duration of care, 90-day charges, and readmission. Multivariate regression was used to assess factors associated with readmission (logistic) and charges (linear). Significance was set at p < 0.01. Results: Patients undergoing 138,842 total hip arthroplasties were discharged to home (18%), home health care (34%), extended-care facilities (35%), and inpatient rehabilitation (13%); patients undergoing 329,233 total knee arthroplasties were discharged to home (21%), home health care (38%), extended-care facilities (31%), and inpatient rehabilitation (10%). Patients in the Northeast were more likely to be discharged to extended-care facilities or inpatient rehabilitation than patients in other regions. Patients in the West had the highest 90-day charges. Approximately 70% of patients were discharged home from extended-care facilities, whereas after inpatient rehabilitation, >50% of patients received home health care. Among those discharged to home, 90-day readmission rates were highest in the South (9.6%) for patients undergoing total hip arthroplasty and in the Midwest (8.7%) and the South (8.5%) for patients undergoing total knee arthroplasty. Having 4 comorbidities, followed by discharge to inpatient rehabilitation or an extended-care facility, had the strongest associations with readmission, whereas the region of the West and the discharge disposition to inpatient rehabilitation had the strongest association with higher charges. Conclusions: Among Medicare patients, discharge disposition and number of comorbidities were most strongly associated with readmission. Inpatient rehabilitation and the West region had the strongest associations with higher charges.