Long-Term Disability and Survival in Traumatic Brain Injury: Results From the National Institute on Disability and Rehabilitation Research Model Systems

Abstract

ObjectivesTo document long-term survival in 1-year survivors of traumatic brain injury (TBI); to compare the use of the Disability Rating Scale (DRS) and FIM as factors in the estimation of survival probabilities; and to investigate the effect of time since injury and secular trends in mortality. DesignCohort study of 1-year survivors of TBI followed up to 20 years postinjury. Statistical methods include standardized mortality ratio, Kaplan-Meier survival curve, proportional hazards regression, and person-year logistic regression. SettingPostdischarge from rehabilitation units. ParticipantsPopulation-based sample of persons (N=7228) who were admitted to a TBI Model Systems facility and survived at least 1 year postinjury. These persons contributed 32,505 person-years, with 537 deaths, over the 1989 to 2011 study period. InterventionsNot applicable. Main Outcome MeasureSurvival. ResultsSurvival was poorer than that of the general population (standardized mortality ratio=2.1; 95% confidence interval, 1.9–2.3). Age, sex, and functional disability were significant risk factors for mortality (P<.001). FIM- and DRS-based proportional hazards survival models had comparable predictive performance (C index: .80 vs .80; Akaike information criterion: 11,005 vs 11,015). Time since injury and current calendar year were not significant predictors of long-term survival (both P>.05). ConclusionsLong-term survival prognosis in TBI depends on age, sex, and disability. FIM and DRS are useful prognostic measures with comparable statistical performance. Age- and disability-specific mortality rates in TBI have not declined over the last 20 years. A survival prognosis calculator is available online (http://www.LifeExpectancy.org/tbims.shtml).