Time-to-Event Analyses: Return to Unrestricted Participation After Sport-Related Concussion in a Cohort of High School Athletes



Document Type

Journal Article

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Publication Title

Journal of athletic training


epidemiology, injury surveillance, recovery, return to play, sports


CONTEXT: Understanding time loss resulting from sport-related concussion (SRC) within individual sports allows high school athletic trainers to provide accurate and evidence-based clinical information. Currently, research regarding patterns of clinical recovery outcomes in high school student-athletes across sports is lacking. OBJECTIVE: To describe the time to authorized unrestricted return to participation (RTP) after SRC in a large cohort of high school student-athletes in a variety of sports using a time-to-event analysis. DESIGN: Descriptive epidemiology study. SETTING: Aggregate injury and player exposure data from the Michigan High School Athletic Association Head Injury Reporting System. PATIENTS OR OTHER PARTICIPANTS: High school student-athletes. MAIN OUTCOME MEASURE(S): Dates for SRC injury events and authorized unrestricted RTP were entered into the Head Injury Reporting System for each case and were used to calculate time to unrestricted RTP. Survival analysis indicated the time to authorized RTP for males and females in weekly increments across sports and academic years. Separate Kaplan-Meier analyses adjusted for SRC cases with a history of concussion also identified the proportions of student-athletes who obtained authorized medical clearance in weekly increments. RESULTS: A total of 15 821 SRCs, 10 375 (65.6%) in males and 5446 (34.4%) in females, were reported during the 2015-2016 through 2018-2019 academic years. The median time to authorized unrestricted RTP was 11 days for all patients. Approximately 30% of concussed student-athletes were not cleared for unrestricted RTP by 14 days after their SRC diagnosis, with 13% taking longer than 21 days to return to unrestricted RTP after SRC. CONCLUSIONS: The results from this multisite, state-based injury surveillance system indicated that it is not abnormal for high school student-athletes to take longer than 14 days to fully recover from an SRC. This information may be useful for educating high school student-athletes and sport stakeholders, normalizing SRC recovery trajectory perceptions, and establishing realistic RTP timeline expectations.

Open Access



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