Aims To examine the associations between socio-economic characteristics and driving under the influence of drugs (DUID), and to elaborate determinants of drugged driving.
Design A register-based case–control study.
Participants Cases (n = 5859) apprehended by the police and suspected of DUID during 1993–2006 and controls (n = 74 809) drawn from the general Finnish population.
Measurements The effects of parents' and own education, urbanization of municipality, socio-economic position (SEP), main activity, income, marital status and living arrangements on DUID were estimated using logistic regression analysis. The analyses were conducted separately for men and women, age groups of under 45 years and aged 45 or over, and for substance groups of benzodiazepines only, benzodiazepines with alcohol, amphetamines and cannabinoids.
Findings Low education, unemployment, disability pension, being divorced and living alone were the strongest individual predictors of DUID in all substance groups. Illicit drug users were more disadvantaged compared to those in the benzodiazepines groups. Contrary to other substance and age groups, higher educational level and higher SEP were associated with DUID among benzodiazepine users aged 45 or over.
Conclusions A disadvantaged social background is a significant predictor of driving while under the influence of drugs for all substance use groups in Finland. The gradient is greater for amphetamines and cannabinoids than benzodiazepines.