Predictors of short-term outcome in brain-injured patients with disorders of consciousness.

OBJECTIVES: To investigate predictors of recovery from the vegetative state (VS) and minimally conscious state (MCS) after brain injury as measured by the widely used Disability Rating Scale (DRS) and to explore differences in rate of recovery and predictors of recovery during inpatient rehabilitation in patients with non-traumatic (NTBI) and traumatic brain injury (TBI). DESIGN: Longitudinal observational cohort design and retrospective comparison study, in which an initial DRS score was collected at the time of study enrollment. Weekly DRS scores were recorded until discharge from the rehabilitation center for both NTBI and TBI patients. SETTING: Seven acute inpatient rehabilitation facilities in the United States and Europe with specialized programs for VS and MCS patients (the Consciousness Consortium). PARTICIPANTS: One hundred sixty-nine patients with a non-traumatic (N=50) and a traumatic (N=119) brain injury who were in the VS or MCS states. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: DRS score at 13 weeks after injury; change in DRS score over 6 weeks post-admission; and time until commands were first followed (for patients who did not show command-following at or within 2 weeks of admission). RESULTS: Both time between injury and enrollment and DRS score at enrollment were significant predictors of DRS score at week 13 post-injury but the main effect of etiology only approached significance. Etiology was however a significant predictor of the amount of recovery observed over the 6 weeks following enrollment. Time between injury and enrollment was also a good predictor of this outcome, but not DRS score at enrollment. For the time until commands were first followed, patients with better DRS scores at enrollment, and those with faster early rates of change recovered command following sooner than those with worse DRS scores or slower initial rates of change. The etiology was not a significant predictor for this last outcome. None of these predictive models explained sufficient variance to allow their use in individual clinical decision making. CONCLUSIONS: Time post-injury and DRS score at enrollment are predictors of early recovery among patients with disorders of consciousness, depending on the outcome measure chosen. Etiology was also a significant predictor in some analyses, with traumatically injured patients recovering more than those with non-traumatic injuries. However, the hypothesized interaction between etiology and time post-injury did not reach significance in any of the analyses suggesting that, within the time frame studied, the decline in prognosis with the passage of time was similar in the two groups.