To determine if functional gain for patients following stroke rehabilitation is adversely affected by osteoarthritis (OA).
A retrospective cohort analysis was conducted using data collected between 1994 and 2001 from a large national registry of US rehabilitation inpatients. Outcome variables were functional status (the Functional Independence Measure [FIM Instrument]) at discharge and followup, FIM gain during and after rehabilitation, length of stay, and discharge setting. The primary predictor variable was the presence of OA. Covariates were age, sex, race, other comorbidities, type of stroke, length of stay, and time to followup. Analysis was by multivariable regression.
Data from 3,094 patients with OA and 44,943 patients without OA admitted following a stroke to inpatient rehabilitation facilities were analyzed. In unadjusted analyses, OA was associated with significantly higher FIM ratings than patients without OA at admission (mean +/- SD 65.7 +/- 19.2 versus 63.1 +/- 20.5; P < 0.001) and discharge (mean +/- SD 89.2 +/- 21.8 versus 87.7 +/- 23.0; P < 0.001), but with lower FIM ratings at followup (mean +/- SD 97.7 +/- 24.7 versus 99.7 +/- 24.9; P < 0.001). In multivariate analyses, adjusting for potential confounders, OA was associated with a 1.62-day increase in length of stay (95% confidence interval [95% CI] 1.15, 2.08) and a 1.37 smaller improvement in FIM scores between admission and followup (95% CI 0.62, 2.12). This smaller increase in FIM instrument score was caused by less improvement in FIM after discharge.
OA impairs recovery from stroke. This is compensated for by longer length of stay for inpatient medical rehabilitation. Reimbursement systems may need to consider the impact of OA as a comorbid condition in patients receiving stroke rehabilitation.