Preliminary study of hearing protection and non-impact, blast-induced concussion in US military personnel.

PRIMARY OBJECTIVE: To examine the relationship between hearing protection and non-impact, blast-induced concussion in US military personnel.

RESEARCH DESIGN: Retrospective cohort study.

METHODS AND PROCEDURES: A total of 501 US service members from the Expeditionary Medical Encounter Database with hearing protection status reported either 'worn' or 'not worn' were eligible for analysis. Clinical records were reviewed for concussion diagnoses. Univariate and multiple logistic regressions were performed.

MAIN OUTCOMES AND RESULTS: Overall, 270 (53.9%) service members sustained non-impact, blast-induced concussion and 231 (46.1%) sustained other blast injuries. Only 39.6% (107 of 270) of service members with concussion wore hearing protection at the point of injury compared with 61.0% (141 of 231) of those with other injuries (p < 0.001). After adjusting for covariates, service members wearing hearing protection had significantly lower odds of concussion compared with those not wearing hearing protection (odds ratio = 0.42, 95% confidence interval = 0.29-0.62).

CONCLUSIONS: To our knowledge, this preliminary study is the first to demonstrate that hearing protection is associated with lower odds of non-impact, blast-induced concussion. The benefits of using hearing protection in terms of force readiness could be significant since many service members wounded in recent conflicts were diagnosed with concussion.