Injury Severity and Outcome: A Meta-Analysis of Prospective Studies on TBI Outcome

Objective: The recent movement to apply evidenced-based approaches to medical and rehabilitation care has increased the importance of approximating outcomes as early in the recovery process as possible. The relationship between injury severity and outcome following traumatic brain injury (TBI), however, has remained unclear due to the variety of predictor and criterion variables used throughout the literature. Method: A meta-analysis of eligible prospective studies that assessed the bivariate association between injury severity and outcome at 1-year postinjury was conducted. Results: Twenty-six studies met the inclusion criteria (total N = 21,050 patients). Injury severity was a significant predictor of outcome at 1-year postinjury (r =.257). Homogeneity testing by means of the Q test, Q(n), indicated that injury severity measurement, Q(68) = 1140.76, p < .00001, outcome measurement, Q(42) = 516.63, p < .00001, and outcome measurement construct, Q(4) = 14.65, p = .006, were significant moderators of the injury severity/outcome link. Further, the magnitude of the effect between injury severity and outcome resulted from a significant interaction between the measure of injury severity and the outcome construct. Conclusions: Overall, measures of injury severity were most significantly associated with measures of global outcome and most poorly associated with measures of satisfaction with life. Additionally, a significant interaction was found between the measure of injury severity and the outcome construct indicating that different measures of injury severity more precisely predict one outcome construct over another. Methodological concerns were discussed and recommendations for creating a more parsimonious and integrated literature base were made.