The risk of subsequent concussion in adolescent ice hockey players with ≥2 concussions

We compared the risk of first and second concussions using Cox models in 11-17-year-old community ice hockey players with ≥2 concussions. Of 4418 participants, 20 participants with ≥2 concussions met our eligibility criteria. Participants without medical clearance had a 4-fold increased risk for second concussion, and those with medical clearance had no increased risk. Playing in a body-checking league did not affect the increase in risk. Although the sample size was small leading to large uncertainty, the results are qualitatively different from previous findings suggesting no increased risk in adults managed according to accepted concussion protocols.