Prevalence of alcohol and other psychoactive substances in injured drivers: Comparison between Belgium and the Netherlands

Study objective: To compare the prevalence of alcohol and (il)licit drugs in seriously injured drivers in Belgium (BE) and the Netherlands (NL). Methods: Injured car and van drivers admitted to the emergency departments of five hospitals in Belgium and three in the Netherlands from January 2008 to May 2010 were included. Blood samples were taken and analysed for ethanol (with an enzymatic method) and 22 other psychoactive substances (UPLC-MS/MS or GC-MS). Results: In total 535 injured drivers were included in the study (BE: 348; NL: 187). More drivers were found positive for alcohol and drugs in Belgium (52.6%) than in the Netherlands (33.9%). Alcohol (≥0.1. g/L) was the most prevalent substance in both countries (BE: 42.5%; NL: 29.6%). A similar prevalence was found for amphetamine (BE: 2.6%; NL: 2.2%) and cocaine (BE: 2.3%; NL: 2.1%). In the Netherlands almost no positive findings for cannabis were recorded (0.5%). No driver tested positive for benzodiazepines in the Netherlands compared to 7.3% in Belgium. More injured drivers tested positive for Z-drugs (BE: 1.8%; NL: 0.5%) and medicinal opioids (BE: 3.3%; NL: 0.5%) in Belgium. Conclusions: The prevalence of alcohol in seriously injured drivers was 12% higher found in Belgium than in the Netherlands. The prevalence of drugs was similar in both countries except for THC and medicinal drugs, particularly benzodiazepines, with a much higher prevalence in Belgium. In comparison to previous survey there were differences in the prevalence of THC, benzodiazepines and combinations of drugs. Possible explanations are the different matrix used, a bias in study population, or in case of illicit opiates and benzodiazepines a different consumption pattern in the two countries. Alcohol is still the most prevalent substance among the injured driver population and this increased the last 15 years.