ABSTRACT
OBJECTIVES: Evaluate yellow card policies' (YCPs) effectiveness in reducing competition contact injuries (CCIs). DESIGN: Retrospective cohort. SETTING: High schools. PARTICIPANTS: Soccer players from High School (HS) Reporting Information Online participating schools, 2005/06 to 2017/18. INDEPENDENT VARIABLES: Athlete exposure (AE), CCIs from HS competitions collected from states with/without YCPs. MAIN OUTCOME MEASURES: Rate and rate ratio (RR) of athlete-athlete CCIs recorded by athletic trainers were compared between states with/without YCPs and pre-YCPs/post-YCPs among the states with YCPs using Poisson regressions. Proportions of severe athlete-athlete CCIs were also described in states with/without YCPs. RESULTS: Fifteen states implemented YCPs between 2005/06 and 2017/18; 901 athlete-athlete CCIs occurred during 352 775 competition AEs in states with YCPs, and 3525 injuries during 1 459 708 competition AEs in states without YCPs. There was no significant difference in injury rates between schools in states with/without YCPs (RR 1.07; 95% confidence interval [CI]: 0.97-1.17). Among state with YCPs, injury rates were not significantly different between pre-YCP and post-YCP implementation (RR 1.15; 95% CI: 0.98-1.34). Although a significantly lower proportion of injuries resulting in >3 weeks' time loss (TL) occurred in states with YCPs (injury proportion ratio 0.81; 95% CI: 0.66-0.997), no significant differences were observed in proportions of other severe athlete-athlete CCIs between states with/without YCPs. CONCLUSIONS: Yellow card policies were ineffective in lowering HS soccer athlete-athlete CCI rates, although injuries resulting in >3 weeks' TL were less prevalent in states with YCPs. Implementation of YCPs alone, without proper enforcement, may not be a sufficient injury prevention strategy.
