Most of the injuries were the result of contact with another person. However, a substantial proportion were caused by contact with either the surface or equipment, according to Zachary Y. Kerr, PhD, MPH, from the University of North Carolina at Chapel Hill, and colleagues.
Because of the public health significance of high school sports–related concussions, ongoing evaluation of the incidence of these concussions is critical to understanding temporal patterns in concussion rates.
With this in mind, the researchers studied the epidemiology of concussions in 20 high school sports during 5 academic years (2013–2014 to 2017–2018).
Boys’ sports included in the study were football, wrestling, soccer, basketball, baseball, cross country, ice hockey, lacrosse, swimming and diving, and track and field. Girls’ sports were volleyball, soccer, basketball, softball, cross country, field hockey, lacrosse, swimming and diving, and track and field. Coed cheerleading was also included.
The investigators examined injury surveillance data for the study period and identified 9542 concussions across the 20 sports.
They defined concussion as injuries that occurred during an organized practice or competition, that required medical attention, and that were diagnosed as concussions.
The researchers calculated concussion rates per athlete exposure (AE) to a practice or competition in particular sports.
Concussions were reported in all 20 sports.
The highest overall concussion rates occurred in boys’ football (10.4 per 10,000 AEs), girls’ soccer (8.19 per 10,000 AEs), and boys’ ice hockey (7.69 per 10,000 AEs).
The lowest rates were in boys’ cross country (0.06 per 10,000 AEs), girls’ cross country (0.13 per 10,000 AEs), and boys’ track and field (0.17 per 10,000 AEs).
When the researchers investigated the mechanism by which the concussions occurred, they found that 62.3% resulted from contact with another person. Most of the remainder were caused by contact with the surface (17.5%) or equipment (15.8%).
During the 5-year study period, football concussion rates rose in association with competitions (33.19 to 39.07 per 10,000 AEs) but dropped in association with practice (5.47 to 4.44 per 10,000 AEs).
Most concussions across all 20 sports occurred during competitions (63.7%); cheerleading was the only one in which the concussion rate was higher during practice (3.60 vs 2.22 per 10,000 AEs).
This is important, the authors note, because not all states recognize cheerleading as a sport. As such, high school cheer squads may practice in less-than-ideal locations, they say, and participants may receive less medical oversight and coaching support than with other sports.
Data for sex-comparable sports showed higher concussion rates for girls than for boys (3.35 vs 1.51 per 10,000 AEs; injury rate ratio [IRR], 2.22; 95% confidence interval [CI], 2.07 – 2.39). Among these sports, girls also had more recurrent concussions (9.3% vs 6.4%; IRR, 1.44; 95% CI, 1.11 – 1.88).
Potential reasons for such differences between the sexes within the same sport have been reported in the literature, the authors write. These include differences in disclosure of injuries, neck musculature, blood flow to the brain, and hormonal regulation.
Concussions were more commonly reported in the latter halves of competitions and practices across numerous sports.
Understanding the epidemiology of concussion and its prevention is critical, especially in light of the rising number of high school athletes and ongoing changes in the field of concussion management.
“Future research should continue to monitor trends and examine the effect of prevention strategies,” they stress. They highlight the need for pediatricians to provide “updated information to youth athletes to help them and their families understand the risk of concussion in their sports of interest.”
The study was supported in part by the Centers for Disease Control and Prevention and by research funding contributions of the National Federation of High School Associations, the National Operating Committee on Standards for Athletic Equipment, DonJoy Orthotics, and EyeBlack. The authors have disclosed no relevant financial relationships.