Long-Term Effects of a Multi-Component Community-Level Intervention to Reduce Single-Vehicle Nighttime Crashes: Follow-Up Findings From a 24-Community Randomized Trial.

OBJECTIVE

This follow-up study examines whether a multi-component, high-visibility alcohol enforcement intervention implemented in 12 California cities had long-term effects on alcohol-related motor vehicle crashes beyond the period of the original study. Previous results indicated a significant reduction in single-vehicle night-time (SVN) crashes among 15- to 30-year-olds in intervention cities relative to controls.

METHOD

A randomized trial was conducted with 24 randomly chosen California cities from 2012 to 2017 to evaluate a multi-component intervention to reduce excessive drinking and driving while impaired among adolescents and young adults. Twelve of the cities were randomly assigned to the intervention condition and implemented high-visibility alcohol enforcement operations and other components from April 2013 to March 2016. Multi-level negative binomial regression analyses were conducted with motor vehicle crash data from 2010 to 2021 to examine whether SVN crashes among 15- to 30-year-olds decreased in intervention cities relative to controls after the multi-component intervention was implemented. Analyses controlled for community sociodemographic characteristics, the overall time trend, the COVID pandemic, and pre-intervention levels of SVN crashes and adjusted for correlation of repeated observations within cities over time.

RESULTS

Regression analyses indicated a significantly lower level of monthly SVN crashes among 15- to 30-year-olds in intervention cities during post-intervention months through 2021 relative to control cities (incidence rate ratio [95% CI] = 0.88 [0.79, 0.98], < .05) when controlling for community sociodemographic characteristics, the overall time trend, COVID, and pre-intervention levels of SVN crashes.

CONCLUSIONS

Study findings suggest that a multi-component, high-visibility alcohol enforcement intervention can have long-term effects on alcohol-related motor vehicle crashes and related injuries and fatalities among adolescent and young adult drivers.