History of concussion and risk of subsequent injury in athletes and service members: A systematic review and meta-analysis.

Risk of secondary injury after a primary concussion in sports and military contexts is an emerging area of interest in research. The purpose of this review was to provide an evidence synthesis describing risk of injury in athletic and military populations with and without a history of concussion. Electronic database searches were completed through September 7, 2018 in PubMed, EMBASE, CINAHL and SCOPUS. Peer-reviewed observational studies of any design with participants who were athletes or service members; measured the outcome of any type of injury; and compared injury between those with and without a history of concussion were included. Risk of bias was assessed using the Q-Coh II. Twenty-seven articles were included. Seventeen meta-analyses were completed for risk of any injury, risk of concussion, and risk of extremity injury using odds, hazard, and rate ratios. The results indicate significantly increased odds of all injuries (OR = 2.55; 95%CI 1.85,3.52); concussion (OR = 3.73; 95%CI 2.41,5.78); and lower extremity injuries (OR = 1.60; 95%CI 1.32,1.94) in those with a history of concussion compared to those without. Additional analyses reveal this increased risk is apparent when looking at time to event data and rate of injury based on number of exposures. While the reasons for the increased incidence of secondary injury associated with a concussion are not yet understood, there are potentially behavioral attributes and motor control deficits that contribute. It is suggested that research is needed to determine if active therapeutic treatment for disturbances in sensorimotor and neuromotor control after concussion could attenuate the increased risk for injury. Published by Elsevier Ltd.