The relationship between drug use and traffic accident severity

The use of alcohol and certain illicit and psychoactive medicinal drugs has been associated with impaired driving and increased accident risk. Data with respect to the relationship between drug use and the severity of the accident, independent of the increased accident risk, are limited. The objective of this chapter is to evaluate and discuss the available epidemiological studies on the relationship between drug use by drivers and the severity of the accident. Data sources used for the literature search were EMBASE, PubMed and Forensic Science Abstracts 3/0 (FORS®). All databases were searched for references included in the database on January 1, 2008. Search strategy included the different groups of psychoactive substances of interest and traffic accidents in combination with accident severity or injury severity. The number of included publications was 20; they were published between 1983 and 2005. The study population varied from all crash-involved drivers (injured and not injured) to patients admitted to a trauma center (including crash-involved drivers) to fatally crash-involved drivers. The most frequently applied design is the cross-sectional study. In general, exposure assessment was performed by using toxicological results but, in a few studies, prescription data, police officers’ observations or questionnaires were used. The effects reported are controversial, i.e. the influence of psychoactive drugs other than alcohol on injury and/or accident severity is not clear. Some discrepancies may be explained by differences in methodological factors, e.g. study population, injury or accident severity measures, and exposure measures.