Alcohol and drug use by Spanish drivers: Comparison of two cross-sectional road-side surveys (2008-9/2013).

Driving under the influence of substances (DUI) other than alcohol has been the subject of increasing interest over the past few decades (Schulze et al., 2012). As with alcohol, research has shown that drug intake increases the risk of road traffic accidents (Elvik, 2013; Schulze et al., 2012; Verstraete & Legrand, 2014). Intervention in this area is a priority. A key factor for deterring DUI is to convince drug-using drivers that the risk of detection is high (Jones, Donnelly, Swift, & Weatherburn, 2006; Watling, Palk, Freeman, & Davey, 2010) thus, adequate law enforcement, and the continuity of roadside testing for drug use among drivers, play an important role (Shepherd, 2001; Watson & Freeman, 2007). For the European Project DRUID (Driving under the Influence of Drugs, Alcohol and Medicines; http://www.druid-project.eu), roadside surveys were conducted in 13 European countries and results showed large differences in the prevalence of alcohol and drug intake by country (Schulze et al., 2012). The highest prevalence was found in Southern Europe (Italy, Spain and Portugal). In Spain, avoiding driving after alcohol or drug use has been recognized as crucial to improving road safety. Five years after the DRUID project, a new roadside survey was conducted following a similar methodology in order to study whether the use of alcohol and drugs among Spanish drivers had changed.