Neuropsychological Predictors of Outcome Following Traumatic Brain Injury in Adults: a Meta-Analysis

Several neuropsychological dimensions are correlated with functional outcome (e.g., ability to return to family and community roles) following traumatic brain injury (TBI). Commonly investigated neuropsychological dimensions include verbal memory, visuo-spatial construction, set-shifting, generativity, and processing speed. Unfortunately, small sample sizes across relevant studies have contributed to inconsistent results. Furthermore, no studies have concurrently measured all of the candidate neuropsychological predictors, most of which are known to be inter-correlated. Thus, the unique predictive effects associated with the candidate predictors in TBI recovery have never been investigated. Consequently, this study used both meta-analysis and multiple regression to statistically evaluate neuropsychological candidate predictors across two outcome variables (1) the Glasgow Outcome Scale-Extended (GOS-E) and (2) the Disability Rating Scale (DRS). Seven studies met inclusion criteria. Based on the meta-analyses, the following neuropsychological dimensions were found to be correlated with the GOS-E: immediate verbal memory (r = .43, 95% CI [.27, .58]), delayed verbal memory (r = .43, 95% CI [.21, .61]), visuo-spatial construction (r = .29, 95% CI [.15, .53]), set-shifting (r = −.31, 95% CI [−.45, −.15], and generativity (r = .44, 95% CI [.32, .54]). By contrast, only one neuropsychological dimension was found to be significantly related to the DRS (generativity: r = −.21, 95% CI [−.39, −.01]). Multiple regression on the GOS-E relevant meta-analytically derived correlation matrix determined that all neuropsychological dimensions were significant predictors of the GOS-E (multiple R² = .31) with the exception of immediate verbal memory or learning. However, due to analytic characteristics, these findings must be interpreted with caution. Results were consistent with the need to consider multiple neuropsychological abilities in recovery and rehabilitation following TBI.