Metodología de reclutamiento y características de una cohorte de jóvenes consumidores habituales de cocaína de tres ciudades espa？olas (Proyecto Itínere-cocaína)

background: health information systems that monitor drug use do not perform in-depth analyses of sociodemographic characteristics and patterns of use, or of the factors that influence health problems. we describe the recruitment methodology and characteristics of a cohort of young cocaine users. methods: a prospective cohort of 720 cocaine users who were not regular heroin users, recruited in the community independently of the health services by chain referral methods in the metropolitan areas of madrid, barcelona and seville was studied. a computer-administered and partially self-administered questionnaire was used. a stratified analysis by city and by frequency of base cocaine use was performed. results: in the previous 12 months, 58.8% had used cocaine 1-2 days/week; 91.9% sniffed it regularly, 5.3 smoked it, and only 2.8% injected it; 6.1% had used it at least half the time in the form of base cocaine. polydrug use was observed with cannabis (93.6%), ecstasy (73.2%) and amphetamines (60.6%). approximately 4.0% had injected at least one drug. crack users (22.1%) had a lower educational level, more intensive cocaine use, a higher prevalence of other drug use, especially opioids, and a much higher prevalence of injection. conclusions: this study confirms and completes the sociodemographic and drug profile provided by the information systems based on health services or population surveys. the results show that a large proportion of young cocaine users consume the drug sporadically and that two very different subpopulations exist, according to whether or not they use base cocaine.