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

Objective: This study examined whether obesity affected inpatient rehabilitation outcomes after total hip arthroplasty (THA).

Methods: 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.

Results: 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%).

Conclusions: 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.