Predicting length of stay after hip or knee replacement for rheumatoid arthritis

To identify predictors of the postoperative length of stay (LOS) after hip or knee replacement for rheumatoid arthritis (RA).

Demographic and clinical characteristics, medications, and postoperative course were abstracted from medical records of patients with RA who underwent total arthroplasties of the knee (TKA) or hip (THA) at our institution between 1987 and 1991. The relationship between these variables and the postoperative LOS was examined using life tables, linear regression, and multiple regression analyses.

During the 5 years of the study, 137 patients with RA underwent 119 TKA and 105 THA. The average LOS was 16.9 +/- 8.7 days after THA and 19.5 +/- 11.4 days after TKA (p = 0.08). Significantly longer LOS was associated with age > or = 55 years, female sex, non-white ethnicity, poor functional status, known positive rheumatoid factor, use of bone cement, and operating room (OR) time longer than 6 hours. In a multivariate regression model, a preoperative Steinbrocker functional class 3 or 4 was associated with an increase in LOS of 3.98 days (95% confidence interval 0.78, 7.18) and 7.14 days (2.59, 11.69), respectively, while a known positive rheumatoid factor predicted an increase in LOS of 2.76 days (0.17, 5.35). Among operative factors, the use of bone cement was associated with a LOS that was longer by 3.50 days (0.80, 6.20), and each hour increase in OR time with a delay in discharge of 1.75 days (1.18, 2.33). Major postoperative wound complications increased LOS by 16.46 days (11.40, 21.52).

Preoperative functional status is an important determinant of the rate of recovery of functional independence after surgery. Strategies for decreasing LOS after hip or knee replacements include optimization of preoperative functional status, early surgical intervention, and prevention of wound complications.