Effect of obesity on inpatient rehabilitation outcomes after total hip arthroplasty.

Abstract

This study examined whether obesity affected inpatient rehabilitation outcomes after total hip arthroplasty (THA). This was a retrospective, comparative study conducted using a computerized medical database derived from THA patients at a university-affiliated rehabilitation hospital (data from 2002 to 2005). Patients were divided into four brackets based on BMI: non-obese (<25 kg/m(2)), overweight (25 to 29.9 kg/m(2)), moderate obesity (30 to 39.9 kg/m(2)), and severe obesity (> or = 40 kg/m(2)). All patients completed an interdisciplinary inpatient rehabilitation program after THA. Functional independence measure (FIM) scores, length of stay (LOS), FIM efficiency scores (FIM/LOS), hospital charges, and discharge disposition location were collected. FIM scores improved from admission to discharge similarly in all groups (25 to 29.5 points). However, FIM efficiency, LOS, and total charges were curvilinearly related with BMI (all p < 0.05). Total hospital charges were highest in the severely obese group compared with the overweight group (p < 0.05). Non-homebound discharge disposition rates were lower in non-obese (13.1%) and severely obese groups (10.5%). Elevated BMI does not prevent FIM gains in THA patients during inpatient rehabilitation. However, BMI is related with FIM efficiency, LOS, and hospital charges in a curvilinear fashion. Severely obese patients can achieve physical improvements but at a lower efficiency and greater cost.