Seasonal and Time-Trend Variation by Gender of Alcohol-Impaired Drivers at Preventive Sobriety Checkpoints.

Abstract

We aimed to analyze the evolution over time and the seasonality of outcomes of nonrandom alcohol concentration breath tests performed on drivers at sobriety checkpoints in Catalonia (Spain) from 2005 to 2012. Differences by gender are also explored. This study was a time-series analysis of the monthly prevalence of drunk drivers by gender. The sample consisted of all drivers tested at nonrandom sobriety checkpoints in Catalonia (N = 3,985,000). Our outcome variable was the monthly prevalence of drivers with a breath alcohol concentration at or above the legal limit. The driver's gender was also registered. A decreasing trend in alcohol-impaired driving over time was found. The gender gap diminished after 2008 and disappeared in 2012. After adjusting for the trend, the lowest monthly coefficient for men was recorded in January (3.91, p < .001) and the highest in July (4.72, p < .001) and September (4.75, p < .001). The lowest monthly coefficient for women was also recorded in January (3.05, p < .001) but the highest in October (4.12, p < .001). After seasonal aggregation, the lowest coefficient was recorded in winter for both men and women, whereas a peak was found for men in spring and for women in autumn. Seasonal patterns for male and female drivers testing positive at nonrandom sobriety checkpoints indicate that the prevalence of alcohol-impaired driving peaks in spring for males and in autumn for females. We recommend that the authorities enforce campaigns that target male and female drinkers accordingly.