Clinical Measures Associated with Subsequent Injury after Adolescent Concussion: A Prospective Cohort Study.

Purpose: To examine associations between clinical measures (self-reported and clinician-administered) and subsequent injury rates in the year after concussion return to play (RTP) among adolescent athletes.

Methods: We performed a prospective, longitudinal study of adolescents ages 13-18 years. Each participant was initially assessed within 21 days of concussion and again within 5 days of receiving RTP clearance from their physician. Participants completed self-report measures: the Pittsburgh Sleep Quality Index (PSQI) and Tampa Scale of Kinesiophobia (TSK), and clinician-administered measures: single and dual-task tandem gait (TG) and reaction time (RT; simple and clinical) assessments. They then completed monthly surveys for a year after RTP which assessed exposure to injury (sport participation) and subsequent injuries (musculoskeletal or concussions) sustained. We used Poisson regression models to calculate injury rate ratios with number of subsequent injuries sustained as the outcome, adjusted for RTP clearance time and competitive exposures for each measure.

Results: 41 participants were included (age = 15.5±1.3 years, 56% female, 9.6±4.6 days post-concussion; 38.0±31.5 days to RTP). A higher injury rate per athletic exposure was observed for simple RT≥505 ms vs <505 ms (injury rate ratio = 3.22; 95% confidence interval = 1.56, 7.12; p = 0.002). Injury rates did not significantly differ by PSQI or TSK scores, single/dual-task TG time, or clinical RT.

Conclusions: Simple reaction time may be one risk factor that is associated with higher rates of subsequent injury after adolescent concussion. A simple reaction time measure incorporated into a comprehensive concussion RTP assessment may identify some individuals at higher risk of subsequent injury in the year following concussion, though further research is needed to better understand this relationship.