Summary of matched variables in the matched cohort
| Entire sample (n=5082) | No helmet (n=2541) | Helmet (n=2541) | P value | |
| Age (years) | 40.9±16.0 | 42.5±15.5 | 39.2±16.4 | <0.001 |
| Sex (male) | 4476 (88.1%) | 2238 (88.1%) | 2238 (88.1%) | 1.000 |
| Race | 1.000 | |||
| Black | 126 (2.5%) | 63 (2.5%) | 63 (2.5%) | |
| Hispanic | 704 (13.9%) | 352 (13.9%) | 352 (13.9%) | |
| Other | 126 (2.5%) | 63 (2.5%) | 63 (2.5%) | |
| White | 4126 (81.2%) | 2063 (81.2%) | 2063 (81.2%) | |
| Comorbidities (1+) | 2370 (46.6%) | 1185 (46.6%) | 1185 (46.6%) | 1.000 |
| Alcohol above legal limit | 372 (7.3%) | 186 (7.3%) | 186 (7.3%) | 1.000 |
| Illegal drug screen | 720 (14.2%) | 360 (14.2%) | 360 (14.2%) | 1.000 |
| Payer | 1.000 | |||
| Medicaid/AHCCCS | 1190 (23.4%) | 595 (23.4%) | 595 (23.4%) | |
| Medicare | 396 (7.8%) | 198 (7.8%) | 198 (7.8%) | |
| Other | 538 (10.6%) | 269 (10.6%) | 269 (10.6%) | |
| Private | 2322 (45.7%) | 1161 (45.7%) | 1161 (45.7%) | |
| Self-pay | 636 (12.5%) | 318 (12.5%) | 318 (12.5%) |
AHCCCS, Arizona Health Care Cost Containment System.