Polysubstance impairment detected in fatally injured drivers, United States, 2018-2022

Polysubstance-impaired driving is an emerging public safety concern. However, research on polysubstance-impaired driving is scant. We used 2018-2022 Fatality Analysis Reporting System data and logistic regression modeling to assess the prevalence of, and factors associated with, polysubstance impairment among drivers aged 14 years and older who died within 1 h of motor vehicle crashes and who had toxicological testing data available (n = 60,741). Polysubstance impairment was defined as having a blood alcohol concentration (BAC) ≥ 0.08 g/dL and testing positive for one or more nonalcohol drugs. The prevalence of polysubstance impairment increased from 14.9% in 2018 to 18.8% in 2022 (p < 0.0001). Cannabis was the most frequently detected nonalcohol drug (25.0%), followed by stimulants (19.2%), and narcotics (8.3%). With adjustment for demographic characteristics, drivers who died in nighttime (7 PM to 6 AM) crashes were almost three times as likely as those who died in daytime (7 AM to 6 PM) crashes to be polysubstance-impaired (adjusted odds ratio [aOR]: 2.94, 95% confidence interval [CI]: 2.80-3.10). Relative to drivers who died in 2018, the odds of polysubstance impairment increased 15% in 2019 (aOR: 1.15, 95% CI: 1.07-1.24), 25% in 2020 (aOR: 1.25, 95% CI: 1.16-1.34), 32% in 2021 (aOR: 1.32, 95% CI: 1.23-1.42) and 38% in 2022 (aOR: 1.38, 95% CI: 1.28-1.49). Results of this study indicate that polysubstance-impaired driving is increasingly involved in fatal motor vehicle crashes. Interventions to reduce polysubstance impairment among drivers are urgently needed for improving traffic safety.