Nonrandomized studies of rehabilitation for traumatic brain injury: Can they determine effectiveness?

Objective: To examine the feasibility of investigating rehabilitation effectiveness for traumatic brain injury (TBI) with a nonrandomized design. Design: Observational cohort with confounder control by regression methodology. Setting: Level I trauma center. Participants: Consecutive series of 365 individuals with TBI discharged to inpatient rehabilitation or home (78% follow-up). Interventions: Not applicable. Main Outcome Measures: The Glasgow Outcome Scale (GOS), Sickness Impact Profile (SIP), Burden Inventory, and Perceived Quality of Life (PQOL). The predictors of interest: discharge to comprehensive inpatient rehabilitation or home and inpatient rehabilitation length of stay (LOS). Results: Discharge to rehabilitation was associated with poorer functioning on the GOS (P=.03) and SIP (P=.57), an increase on the Burden Inventory (P=.14), and improved PQOL (P=.20). Similar results were found for longer lengths of inpatient rehabilitation. Conclusions: The results appear to be because of a confounding effect rather than rehabilitation. The study design could not control for confounding that resulted from unmeasured or difficult to measure aspects of the clinical decisions for discharge placement and rehabilitation LOS. Furthermore, typical severity indices were inadequate to control for injury severity and recovery. Matching designs that investigate TBI rehabilitation are also at risk for inadequate confounder control.