Prevalence and predictors of driving under the influence of alcohol in Switzerland: A mandatory roadside survey

OBJECTIVE: This nationwide roadside survey aimed to determine the prevalence of driving under the influence of alcohol (DUI) among car drivers in Switzerland and identify associated factors. METHODS: Adhering to the European study Baseline guidelines, the survey was stratified by road type, time window, and language region. Fourteen police corps conducted controls across areas representing 59% of the Swiss population. Locations were determined in randomly selected municipalities. Drivers were stopped randomly or via road blockage, and all were tested for alcohol. Logistic regression models were used to analyze predictors of DUI, both in terms of driving with a detectable alcohol concentration [>0 milligram of alcohol per liter of breath (mg/l)] and driving with concentrations above the legal limit (0.25 mg/l for most drivers; 0.05 mg/l for specific groups, e.g., novice drivers). The models accounted for potential influencing factors, and data were weighted to ensure representativeness. RESULTS: Of 4,847 drivers tested, 3.6% had detectable alcohol levels, and 0.4% exceeded the legal limit. Male drivers, individuals aged 31 years or older, and those departing from restaurants, bars, or parties had a higher prevalence of driving with detectable alcohol levels or levels above the legal limit. Drivers in the French-speaking region were more likely to have detectable alcohol concentrations than those in the German-speaking region, although no significant regional difference was found for exceeding the legal limit. The prevalences of driving with a detectable alcohol concentration and of exceeding the alcohol limit were higher at night, on weekends, and tended to be higher on urban roads compared to rural roads or motorways. Exceeding the limit was more common in fine weather than in cloudy or rainy conditions. CONCLUSIONS: Switzerland has a relatively low prevalence of exceeding the alcohol limit compared to other European countries. However, male gender, older age, nighttime and weekend driving, and social drinking contexts increased DUI risk. Continued monitoring and targeted interventions addressing high-risk groups, locations, and times are essential for enhancing road safety.