Cocaine use in Europe - a multi-centre study: patterns of use in different groups.

AIM The study investigates patterns of cocaine powder and crack cocaine use of different groups in nine European cities. DESIGN, SETTING, PARTICIPANTS Multi-centre cross-sectional study conducted in Barcelona, Budapest, Dublin, Hamburg, London, Paris, Rome, Vienna, and Zurich. Data were collected by structured face-to-face interviews. The sample comprises 1,855 cocaine users out of three subgroups: 632 cocaine users in addiction treatment, mainly maintenance treatment; 615 socially marginalized cocaine users not in treatment, and 608 socially integrated cocaine users not in treatment. MEASUREMENTS Use of cocaine powder, crack cocaine and other substances in the last 30 days, routes of administration, and lifetime use of cocaine powder and crack cocaine. FINDINGS The marginalized group showed the highest intensity of cocaine use, the highest intensity of heroin use and of multiple substance use. 95% of the integrated group snorted cocaine powder, while in the two other groups, injecting was quite prevalent, but with huge differences between the cities. 96% of all participants had used at least one other substance in addition to cocaine in the last 30 days. CONCLUSIONS The use of cocaine powder and crack cocaine varies widely between different groups and between cities. Nonetheless, multiple substance use is the predominating pattern of cocaine use, and the different routes of administration have to be taken into account.