Relationships of Changing State Cannabis Policies With Alcohol Policy Effectiveness and Alcohol or Cannabis Involvement in Motor Vehicle Fatalities.

Abstract

Alcohol use is an established and important risk factor for motor vehicle crashes and crash fatalities. The liberalization of cannabis policy across U.S. states could impact motor vehicle crash fatalities involving alcohol or the co-use of alcohol and cannabis. Mortality data were from the Fatality Analysis Reporting System in 50 states and Washington, DC, from 2010 to 2019. State-year alcohol policy scores and cannabis policy scores were used as measures of policy exposure in multivariable mixed logistic regression models to estimate the AOR of 2 blood alcohol concentration thresholds and/or any detectable tetrahydrocannabinol involvement in crash fatalities. In fully adjusted models, a 10-percentage point increase in alcohol policy scores (representing more robust alcohol control policies) was associated with a 6.3% lower risk of a blood alcohol concentration >0.00% (AOR=0.937; 95% CI=0.886, 0.991) or involvement at a blood alcohol concentration ≥0.08% (AOR=0.938; 95% CI=0.888, 0.992) among motor vehicle crash decedents. However, there were no significant independent association between cannabis policy scores and alcohol involvement. A 10-percentage point increase in cannabis policy scores (representing more robust cannabis control policies) was associated with reduced odds of cannabis involvement (AOR=0.956; 95% CI=0.922, 0.991) or alcohol and cannabis coinvolvement (AOR=0.962; 95% CI=0.928, 0.997). More restrictive alcohol policies and cannabis policies were associated with reduced odds of motor vehicle crash fatalities involving alcohol and cannabis, respectively. Cannabis policies did not affect protective associations between alcohol policies and alcohol involvement. However, more restrictive cannabis policies were protective for coinvolvement of alcohol and cannabis.