Cross-Walk Comparison of the DVBIC-TBICoE and LIMBIC-CENC Combat-Related Concussion Prospective Longitudinal Study Datasets.

OBJECTIVE: To describe and compare cohorts between 2 large, longitudinal, federally-funded TBI studies of Service members and veterans across demographic, self-report, and neuropsychological variables. DESIGN: Analysis of data from the DVBIC-TBICoE and LIMBIC-CENC prospective longitudinal studies (PLS). SETTING: Recruitment locations spanning Department of Defense and Veterans Affairs hospitals across the U.S. PARTICIPANTS: 1463 participants (N=1463) enrolled in the DVBIC-TBICoE study and divided among non-injured (NIC) (n=191), injured control (IC) (n=349), mild TBI (mTBI) (n=682), and (severe, moderate, penetrating, and complicated mild traumatic brain injury (smcTBI) (n=241) subgroups. 1550 participants enrolled in the LIMBIC-CENC study and divided between IC (n=285) and mTBI (n=1265) subgroups. IC and mTBI study groups were compared across demographic and military characteristics, self-reported symptoms, and neuropsychological test scores. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Neurobehavioral Symptom Inventory, PTSD Checklist-Military Version, TBI quality of life, Test of Premorbid Functioning, Wechsler Adult Intelligence Scale-IV Visual Puzzles, Symbol Search, Coding, Letter-Number Sequencing, and Digit Span, Trail Making Test, Delis-Kaplan Executive Functioning System Verbal Fluency, Letter Fluency, and Category Fluency, California Verbal Learning Test-II, and Grooved Pegboard. RESULTS: Compared with DVBIC-TBICoE, LIMBIC-CENC participants have higher enrollment age, education level, proportion of Black race, and time from injury as well as less combat deployments and are less likely to be married. The distribution of military service branches also differed. Further, symptom profiles differed between cohorts. LIMBIC-CENC participants endorsed higher posttraumatic stress disorder symptomatology. DVBIC-TBICoE study IC participants endorsed higher somatosensory and vestibular symptoms (medium effect sizes). Other symptom measure differences had very small effect sizes (≤0.2). Differences were found on many cognitive test results, but are difficult to interpret given the demographic differences and generally very small effect sizes. CONCLUSIONS: The heavy use of National Institutes of Health common data elements in both studies and collaboration with the DVBIC-TBICoE study team on development of the LIMBIC-CENC assessment battery enabled this comparative analysis. Results highlight unique differences in study cohorts and add perspective and interpretability for assimilating past and future findings.

Surveying the Landscape: A Review of Longitudinal Traumatic Brain Injury Studies in Service Member and Veteran Populations.

Traumatic brain injury (TBI) is known to be a signature wound of the post-9/11 conflicts. In response, the U.S. Department of Defense (DOD) and other federal organizations have directed significant investments toward TBI research on characterizing injury populations and understanding long-term outcomes. To address legislative requirements and research gaps, several observational, longitudinal TBI studies were initiated as an effective means of investigating TBI clinical management, outcomes, and recovery. This review synthesizes the landscape (i.e., requirements and gaps, infrastructure, geography, timelines, TBI severity definitions, military and injury populations of interest, and measures) of DOD-funded longitudinal TBI studies being conducted in service member and veteran (SMV) populations. Based on the landscape described here, we present recommended actions and solutions that would allow a consolidated and cooperative future state of longitudinal TBI research, optimized continued investments, and advances in the state of the science without redundancy.