Bicycle Helmet Influence in the New Millennium on United States Head, Traumatic Brain Injury, Upper and Lower Body Injury Rates

This study compares cycling participation and helmet wearing survey results with bicycle-related total injuries, head injuries, traumatic brain injuries and upper/lower body injuries for all-ages, youth and adults who presented to emergency departments or were hospitalized in the United States from 2001 to 2020. Demographic increases/decreases in bicycle-related total injuries concur with participation survey trends, and this is reflected through injury trends for body parts not influenced by helmet wearing. The decrease in 0-17yo total ED presentations from 2001-2010 to 2011-2020 was greater than the decrease in head injuries but the decrease in total hospital admissions was less than the decrease in hospitalized head injuries. The TBI proportion of 0-17yo head injury ED presentations increased significantly, and to a lesser extent among hospitalized head injuries. 18yo+ head injury ED presentations increased at a significantly greater rate than total injuries from 2001-2010 to 2011-2020. 18yo+ hospital admissions more than doubled and head injuries increased 81.6%. The TBI proportion among 18yo+ ED head injuries increased by 9%, while the hospitalized head injury TBI proportion increased from 84.2% to 86.8%. Future studies should examine the relationship between cycling participation and head injuries to determine why total youth injuries including head injury declines were commensurate with participation declines, why adult total injuries including head injuries increased at rates above estimated participation trends, and why the TBI proportion of head injuries has increased despite a greater number of cyclists wearing helmets since 2001.