A multicenter examination of the Center for Medicare Services eligibility criteria in total-joint arthroplasty.

OBJECTIVE: The Centers for Medicare and Medicaid Services (CMS) use a diagnostic category (revised in 2004) as one of eight criteria to determine whether a hospital is eligible for payment as an inpatient rehabilitation facility (IRF). Among the 13 specific categories of patients, there are three particular ones involving total knee arthroplasty (TKA) and hip arthroplasty (THA) patients. The purpose of this investigation was to analyze inpatient rehabilitation outcomes in TKA and THA patients, using these CMS criteria.

DESIGN: A multicenter, retrospective study using a consecutive patient sample from 15 independent inpatient rehabilitation facilities, conducted from January 1, 2002 through March 31, 2006. All patients had either primary or revision TKA or THA and were directly admitted for inpatient rehabilitation postacute care. Patients were 23,274 men and women, separated into three comparison pairs on the basis of CMS eligibility criteria: (1) unilateral or bilateral arthroplasty, (2) age <85 yrs or >or=85 yrs, or (3) body mass index (BMI) <50 or >or=50 kg/m2. All patients underwent a comprehensive rehabilitation program that included physical and occupational therapies for 3 hrs/day. Main outcomes were inpatient rehabilitation length of stay (LOS), functionality as assessed by the FIM instrument, FIM efficiency, hospital charges, and discharge disposition.

RESULTS: FIM efficiency scores were 8-21% lower in bilateral arthroplasties and patients aged >or=85 yrs, respectively (P < 0.0001). LOS was an average of 33% longer in patients >or=85 yrs than among patients <85 yrs (3.4 days; P < 0.0001). Total charges were 12-30% higher for patients with BMI >or=50 kg/m and >85 yrs than their comparative groups (P < 0.001). Arthroplasty patients <85 yrs were discharged more often to home compared with those >or=85 yrs (P = 0.0001). Patients >or=85 yrs were more likely to be transferred to a skilled nursing facility (7.4%) or back to acute care (3.9%) than those <85 yrs.

CONCLUSIONS: All arthroplasty patients demonstrated improved physical function after inpatient rehabilitation. Those aged >or=85 yrs demonstrated the lowest efficiency, the greatest cost, and were the least likely to return home.