Cocaine use among heroin users in Spain: The diffusion of crack and cocaine smoking

Study objective - To describe the prevalence and patterns of use of crack and cocaine hydrochloride among heroin users in Spain. To explore if the expansion of heroin smoking is accompanied by a similar phenomenon for cocaine. Design - Cross sectional study in 1995. Face to face interviews using a structured questionnaire. Setting - Three cities with different prevalences of heroin use by smoking: high (Seville), intermediate (Madrid), and low (Barcelona). Participants - 909 heroin users, 452 in treatment and 457 out of treatment. Main results - Last month prevalence of crack use was 62.3% in Seville, 19.4% in Madrid, and 7.7% in Barcelona. Most users in Madrid (86.5%) and Barcelona (100%) generally prepared their own crack, usually with ammonia as alkali; in Seville most users (69.7%) bought preprocessed crack. The proportion of users who began taking cocaine (crack or cocaine hydrochloride) by smoking has increased progressively since the seventies, rising to 74.1% in Seville, 61.5% in Madrid, and 28% in Barcelona in 1992-1995, with the earliest increase in Seville. The factors associated with crack use were: residence in Seville (odds ratio (OR) = 16.3), cocaine hydrochloride use mainly by smoking (OR = 5.0), by sniffing (OR = 2.7) or by injecting (OR = 2.5), heroin use mainly by smoking (OR = 2.8) and weekly use of cannabis (OR = 1.9). Conclusions - In Spain smoking cocaine may be progressively diffusing from the south west to the north east, similar to what has happened with smoking heroin, but beginning later in time. The factors associated with smoking cocaine are basically ecological or cultural in nature (characteristics of the available drugs and the main route of heroin administration in each city).