Restraint use death risk ratios (RRs)*
| Restraint use | Age (years) | Survived | Died | RR (95% CI) | Wald p value |
| Seatbelt with booster | 4–5 | 492 | 182 | 0.33 (0.28 to 0.40) | |
| 6–8 | 84 | 40 | 0.45 (0.31 to 0.63) | <0.005 | |
| Seatbelt | 4–5 | 981 | 371 | 0.37 (0.32 to 0.43) | |
| 6–8 | 1319 | 541 | 0.39 (0.34 to 0.44) | 0.61 | |
| Unrestrained | 4–5 | 627 | 445 | Ref. | |
| 6–8 | 712 | 437 | Ref. | ||
| Unknown† | 4–5 | 217 | 92 | – | |
| 6–8 | 226 | 85 | – | ||
| Total | 4658 | 2193 | – |
*Comparing restraint use vs no restraint and adjusted for age, sex, exposure to air bag deployment, seating position, adult seatbelt use, and all matched collision and vehicle characteristics.
†Partially or fully unknown restraint use was assigned to other values of restraint use by multiple imputation.