Most common multiple-substance-use problems and odds ratios (ORs) among first-aid station visitors (%).

Alc = alcohol. Amp = amphetamines. Can = cannabis. Coc = cocaine. Ecs = ecstasy.More than one symptom can occur in combination with the two combined substances.Reference category for the logistic regression analysis is not reporting the use of each combination of the substances.95% CI = 95% confidence interval (lower-upper).ORs are available only for variables included in the forward stepwise model.