| Helmet(n = 5857) | No helmet(n = 5732) | p Value | |
| Female (%) | 40.2 | 59.8 | <0.001 |
| Mean age (years) | 25.0 | 27.7 | <0.001 |
| <15 (%) | 26.4 | 24.1 | <0.001 |
| 15–24 (%) | 30.7 | 27.3 | <0.001 |
| 25–34 (%) | 16.3 | 14.3 | <0.001 |
| 35–64 (%) | 23.7 | 27.3 | <0.001 |
| 65+ (%) | 1.0 | 3.2 | <0.001 |
| Unknown (%) | 1.8 | 3.7 | |
| Race (%) | <0.001 | ||
| Asian or Pacific Islander | 0.2 | 0.1 | |
| Black | 1.9 | 3.0 | |
| Hispanic | 2.5 | 3.7 | |
| Native American or Alaskan Native | 0.2 | 0.5 | |
| Other | 5.6 | 4.5 | |
| White, non-Hispanic | 86.0 | 83.5 | |
| Missing race | 3.6 | 4.8 | |
| US region (%) | <0. 001 | ||
| Midwest | 28.4 | 40.0 | |
| Northeast | 27.2 | 2.9 | |
| South | 24.3 | 39.8 | |
| West | 20.1 | 17.3 | |
| Injury Severity Score (mean) | 11.1 | 11.9 | <0.001 |
| Revised Trauma Score (mean) | 7.6 | 7.4 | <0.001 |
| Glasgow Coma Score (mean) | 14.3 | 13.6 | <0.001 |
| AIS⩾3 by region (%) | |||
| Head | 6.6 | 17.2 | <0.001 |
| Face | 0.7 | 1.4 | <0.001 |
| Neck | 0.1 | 0.3 | <0.05 |
| Thorax | 11.0 | 12.2 | <0.05 |
| Abdomen | 3.8 | 3.9 | NS |
| Spine | 5.2 | 5.0 | NS |
| Upper extremity | 3.7 | 3.3 | NS |
| Lower extremity | 8.6 | 7.8 | NS |
| Major traumatic brain injury (AIS⩾4) (%) | 3.2 | 9.3 | <.001 |
| Spinal cord injury (%) | 1.8 | 1.4 | NS |
AIS, Abbreviated Injury Scale.