Association between state-level syncope driving policies and motor vehicle crash rates in the United States

To evaluate whether jurisdiction-level mandatory physician reporting requirements and minimum driving-restriction duration after syncope or another relevant loss-of-consciousness event are associated with motor vehicle crash and fatality rates.

This cross-sectional ecological study included the 50 U.S. states and the District of Columbia. Two policy domains were evaluated independently: mandatory versus nonmandatory physician reporting and minimum driving restrictions of less than 6 months versus 6 months or longer. Crash and fatality outcomes were normalized to licensed drivers, population, or registered vehicles. Primary analyses used unweighted, two-sided Welch t tests. Sensitivity analyses of older-driver crash rates incorporated separate adjustment for annual precipitation, average temperature, and urban-to-rural road mileage; denominator-weighted least-squares models weighted by the number of licensed older drivers; and leave-one-mandatory-jurisdiction-out analyses.

Six jurisdictions mandated physician reporting. Primary older-driver crash analyses included 49 jurisdictions. Older-driver crash rates were lower in mandatory-reporting jurisdictions than in nonmandatory-reporting jurisdictions (1,232.54 versus 2,217.85 per 100,000 licensed older drivers; mean difference, -985.32; 95% CI, -1,774.32 to -196.31; p = 0.020). The older-to-young crash-rate ratio was also lower (0.19 versus 0.27; mean difference, -0.086; 95% CI, -0.153 to -0.019; p = 0.015). The association with older-driver crash rates remained significant after each ecological adjustment and in the denominator-weighted model (810.0 versus 2,405.9; coefficient, -1,595.9; 95% CI, -2,237.1 to -954.8; p < 0.001), as well as after sequential exclusion of each mandatory-reporting jurisdiction. Minimum restrictions of 6 months or longer were not significantly associated with older-driver crash rates in the primary unweighted comparison (1,830.10 versus 2,314.84; mean difference, -484.73; 95% CI, -1,091.80 to 122.33; p = 0.115), but were associated with lower rates in the denominator-weighted model (1,677.2 versus 2,593.9; coefficient, -916.8; 95% CI, -1,816.8 to -16.8; p = 0.046). This weighted association remained significant after adjustment for temperature but not after adjustment for precipitation or urban-to-rural road mileage. No significant fatality-rate differences were observed for either policy domain.

Mandatory physician reporting was consistently associated with lower older-driver crash rates across primary and sensitivity analyses. Longer minimum restriction duration showed a supportive but model-dependent association. These findings suggest that an organized reporting and medical-review pathway may be more consequential than restriction duration alone, but the ecological design does not establish causality or individual driving risk.