title: A preliminary examination of the CMS eligibility criteria in total-joint arthroplasty.
abstract: OBJECTIVE
  To analyze inpatient rehabilitation outcomes in total-knee arthroplasty (TKA) and total-hip arthroplasty (THA) patients using the 2004 Medicare 75% rule criteria.
  
  
  METHODS
  This retrospective study compared outcomes in unilateral TKA (UTKA), bilateral TKA (BTKA), and THA after interdisciplinary inpatient rehabilitation (n = 867). Patients were separated into three comparison pairs: 1) UTKA or BTKA, 2) age <85 yrs or > or =85 yrs, and 3) body mass index (BMI) <50 or > or =50 kg/m. Length of stay (LOS), functional independence measure (FIM) scores (total, motor, and cognitive), hospital charges, FIM efficiency, and discharge disposition were analyzed.
  
  
  RESULTS
  BTKA improved total FIM score more than UTKA (43 vs. 38%; P = 0.039). TKA with BMI > or =50 kg/m had similar admission and discharge FIM motor scores compared with BMI <50 kg/m (P > 0.05). TKA patients > or =85 yrs had lower admission FIM scores, longer LOS (11.3 vs. 9.4 days), and 22% higher total charges than TKA patients younger than 85 yrs (P = 0.042). THA patients > or =85 yrs had 6-10% lower total FIM, FIM motor, and FIM cognition scores and were discharged to home less frequently than younger patients (P < 0.05). Total and daily charges were 21-162% higher in THA patients with BMIs > or =50 kg/m than in THA patients with BMIs <50 kg/m (P < 0.045).
  
  
  CONCLUSIONS
  All patients made functional gains during rehabilitation. However, the most costly and lengthy rehabilitation occurred in TKA patients > or =85 yrs and THA patients with BMI > or =50 kg/m.
authors.affiliation: Department of Physical Medicine and Rehabilitation, University of Virginia Health System, Charlottesville, Virginia 22908-1004, USA.
authors.forename: Kevin R
authors.initials: KR
authors.lastname: Vincent
authors.forename: Laura W
authors.initials: LW
authors.lastname: Lee
authors.forename: Jenpin
authors.initials: J
authors.lastname: Weng
authors.forename: Alan P
authors.initials: AP
authors.lastname: Alfano
authors.forename: Heather K
authors.initials: HK
authors.lastname: Vincent
mesh_terms: D000203:Activities of Daily Living; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000534:rehabilitation*; D019645:Arthroplasty, Replacement, Knee / Q000534:rehabilitation*; D015992:Body Mass Index; D014487:Centers for Medicare and Medicaid Services, U.S.; D004608:Eligibility Determination / Q000592:standards*; D005260:Female; D017722:Hospital Charges / Q000706:statistics & numerical data; D006801:Humans; D007297:Inpatients; D007902:Length of Stay; D008297:Male; D017063:Outcome Assessment, Health Care; D010348:Patient Care Team; D012189:Retrospective Studies; D014481:United States