Post-Traumatic Stress Disorder Is A Stronger Predictor Of Long-Term Neurobehavioral Outcome Than Traumatic Brain Injury Severity In Us Military Service Members

Abstract Objective The purpose of this study was to examine long-term neurobehavioral outcome in SMVs with versus without PTSD following TBI of all severities. Methods Participants were 536 SMVs recruited into three experimental groups (TBI, injured controls [IC], non-injured controls [NIC]). Participants completed the PTSD Checklist and the TBI-Quality of Life (TBI-QOL). Participants were divided into six subgroups based on the three experimental categories, two PTSD categories (i.e., present/absent), and two broad TBI severity categories (i.e., ‘unMTBI’ [includes uncomplicated mild TBI]; and ‘smcTBI’ [includes severe TBI, moderate TBI, and complicated mild TBI): (1) NIC/PTSD-Absent, (2) IC/PTSD-Absent, (3) unMTBI/PTSD-Absent, (4) unMTBI/PTSD-Present, (5) smcTBI/PTSD-Absent, and (6) smcTBI/PTSD-Present. Results There were significant main effects across the six groups for all TBI-QOL measures (p < .001). Select pairwise comparisons revealed significantly worse scores (p < .001) on all TBI-QOL measures in all PTSD-Present groups compared to the PTSD-Absent groups (i.e., Group 3v4 and 5v6; d = 0.90 to 2.11). In contrast, when controlling for PTSD, there were no significant differences between the TBI severity groups for all TBI-QOL measures (i.e., Group 3v5 and 4v6). In the TBI sample, a series of step-wise regression analyses revealed that PTSD, but not TBI severity, was consistently a strong predictor of all TBI-QOL scales (all p’s < .001), accounting for up to 64% of the variance. Conclusions These results provide support for the very strong influence of PTSD, but not TBI severity, on long-term neurobehavioral outcome following TBI. Concurrent PTSD and TBI of all severities should be considered a risk factor for poor long-term neurobehavioral outcome that requires ongoing monitoring.