Epidemiology and prognosis of mild traumatic brain injury in returning soldiers: A cohort study.

Objective: Mild traumatic brain injury (mTBI; concussion) is common in returning service members yet limited definitive evidence exists on its prognosis.

Methods: Almost 25,000 non-medically evacuated soldiers returning from Afghanistan or Iraq to 2 military bases between 2009 and 2014 were screened for mTBI. We invited a random sample to participate in the present study, oversampling those screening positive, resulting in 557 mTBI cases and 1,010 controls, of whom 366 cases and 599 controls completed 3-month follow-up evaluations. The criterion measure of screened mTBI was the Ohio State University Traumatic Brain Injury Identification Method. Postconcussive symptoms (PCS) were measured at follow-up with the Neurobehavioral Symptom Inventory. Symptoms reported at a severe or very severe level were considered clinically relevant.

Results: About half (47%) of soldiers who had sustained an mTBI during this latest deployment reported PCS at 3-month follow-up vs 25% of controls: adjusted odds ratio 2.4 (1.8-3.2). The most commonly reported symptoms (cases vs controls) were sleep problems (30% vs 14%), forgetfulness (21% vs 9%), irritability (17% vs 8%), and headaches (15% vs 5%). mTBI cases were about twice as likely as controls to report receiving rehabilitative services and fair or poor health. Other predictors of PCS included posttraumatic stress, combat exposure, and noncephalic pain. A majority of both cases and controls reported traumatic brain injuries predating this latest deployment.

Conclusions: In this nonclinical population of recently deployed soldiers, a substantial proportion of those who had sustained an mTBI were symptomatic 3 months postdeployment. Future studies need to include longer follow-up to measure symptom resolution.

Clinicaltrialsgov Identifier: NCT01847040.