About 15% of the U.S. high school population -- 2.5 million students -- self-reported having at least one concussion related to sports or physical activity over a 1-year period, according to the CDC.
This prevalence is higher than emergency department estimates (622.5 visits per 100,000 population ages 10-14 ) and athletic trainer reports (1.8 per 100 high school and college athletes for an average season), according to the CDC's Lara DePadilla, PhD, and co-authors.
"Emergency department data miss concussions treated elsewhere, and athletic trainer reports miss concussions sustained outside of school-based sports; both sources miss medically untreated concussions," the researchers wrote in Morbidity and Mortality Weekly Report.
Overall, 9.1% of high school students reported having one concussion and 6.0% reported having two or more concussions in the 12-month period.
Concussion prevalence was significantly higher among males and among all students who played team sports. Concussion odds also grew with the number of team sports played.
The findings are part of the Youth Risk Behavior Survey (YRBS), a cross-sectional study of 14,765 public and private school students in grades 9 through 12. In 2017, the CDC included a question about concussions on the national YRBS questionnaire for the first time.
A recent study found that 40% of high school athletes who experienced concussions said their coach was unaware of their symptoms.