Variable, model | Sample | P value for helmet use | OR (95% CI) | Interpretation |

Helmet use, adjusted model | Matched cohort | <0.001 | 0.44 (0.31 to 0.58) | For each death, a 56% decrease in odds of wearing a helmet |

Helmet use, adjusted model | Entire sample | <0.001 | 0.46 (0.35 to 0.61) | For each death, a 54% decrease in odds of wearing a helmet |