What is the risk of recurrent concussion in children and adolescents aged 5-18 years? A systematic review and meta-analysis.

OBJECTIVE: We aimed to examine the risk of concussion in children with a previous history of concussion.
DESIGN: Systematic review and meta-analysis. The primary outcome was number of children with and without a previous lifetime history of concussion who sustained a diagnosed concussion within each study period. Risk of bias was assessed using the Newcastle-Ottawa Scale. A random effects model was used to estimate a pooled risk ratio (RR) with corresponding 95% CIs; results were summarised in forest plots. DATA SOURCES: Four electronic databases (MEDLINE, Embase, CINAHL, SPORTDiscus) and selected reference lists were searched (PROSPERO registration No CRD42019135462). ELIGIBILITY CRITERIA: Original English language peer-reviewed publications that compared concussion risk in children aged 5-18 years with and without a previous concussion history in which risk estimates were reported or able to be calculated.
RESULTS: Of 732 identified studies, 7 studies representing 23 411 children (risk of bias range, 7-9; maximum possible score=9) were included for meta-analysis. Pooled risk of sustaining a concussion was more than three times greater in children with a previous concussion compared with those with no previous concussion (RR=3.64; 95% CI: 2.68 to 4.96; p<0.0001; I 2=90.55%). Unreported sex-stratified data precluded direct comparison of concussion risk in male versus female athletes.
CONCLUSION: Previously concussed children have four times the risk of sustaining a concussion compared with those with no previous concussion history. This should be a consideration for clinicians in return to sport decision-making. Future studies examining subsequent recurrent concussion in youth sports must consider sex differences. © Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.