Mild traumatic brain injury (concussion) during combat: lack of association of blast mechanism with persistent postconcussive symptoms.

OBJECTIVE

To determine whether screening for a blast mechanism of concussion identifies individuals at higher risk of persistent postconcussive symptoms (PCS).

SETTING

United States Army post.

PARTICIPANTS

3952 US Army infantry soldiers were administered anonymous surveys 3 to 6 months after returning from a yearlong deployment to Iraq.

MAIN OUTCOME MEASURES

Self-reported concussion (defined as an injury that resulted in being "dazed, confused, or 'seeing stars'"; "not remembering the injury"; or "losing consciousness [knocked out]): Patient Health Questionnaire 15-item scale for physical symptoms and PCS; Posttraumatic Stress Disorder Checklist; and Patient Health Questionnaire depression module.

RESULTS

Of the 587 soldiers (14.9% of the total sample) who met criteria for concussion, 201 (34.2%) reported loss of consciousness, and 373 (63.5%) reported only an alteration of consciousness without loss of consciousness; 424 (72.2%) reported a blast mechanism, and 150 (25.6%) reported a nonblast mechanism. Among soldiers who lost consciousness, blast mechanism was significantly associated with headaches and tinnitus 3 to 6 months postdeployment compared with a nonblast mechanism. However, among the larger group of soldiers reporting concussions without loss of consciousness, blast was not associated with adverse health outcomes.

CONCLUSIONS

Blast mechanism of concussion was inconsistently associated with PCS, depending on the definition of concussion utilized. A self-reported history of blast mechanism was not associated with persistent PCS for the majority of US soldiers with concussions.