Poly-drug findings in drugged driving cases during 1977-2007

Background: Driving under the influence of drugs (DUID) is an increasing public health and traffic safety related problem. We examined the poly-drug findings and their trends among all apprehended DUID offenders in Finland.Methods: A register data from 1977 to 2007 was analysed. The data included a total of 31,963 suspected DUID cases with a positive finding for an illicit/licit drug impairing driving performance. Blood and/or urine specimens were analysed in one central laboratory.Results: Poly-drug findings were common among suspected DUID cases during the entire study period. Seventy-seven per cent of the specimens had a finding from two or more substance groups. Benzodiazepines with alcohol (20% of poly-drug cases) and amphetamines with benzodiazepines (18%) were the most frequently found combinations. Benzodiazepines were present in the five most frequent combinations. The proportion of cases including drugs only increased more rapidly than the proportion of cases including a combination of drugs and...