[Cohort study methodology of the ITINERE Project on heroin users in three Spanish cities and main characteristics of the participants].
BACKGROUND
Cohort studies make it possible to monitor the health impact of drug use and to identify related factors. We describe the methodology and baseline characteristics of a cohort of heroin users designed with this objective.


METHODS
The participants were 991 young, community-recruited heroin users in Barcelona, Madrid and Seville. Most subjects were named by other participants (39.7%) or by non-participating drug users or ex-users (44.7%). A computer-aided questionnaire was administered (self-administered with audio for questions related with sex). A dried-blood spot sample was collected and anthropometric measurements were made. Both participants and recruiters received remuneration. Univariate and bivariate statistical methods were used.


RESULTS
Some 42.4% had changed the main route of heroin administration, mainly to injection in Barcelona and to the pulmonary route in Seville. About 75.8% (Barcelona), 49.8% (Madrid), and 15.5% (Seville) had injected drugs in the last 12 months. In Madrid and Seville, 96-97% used heroin in base form, while in Barcelona heroin hydrochloride predominated. Heroin and cocaine were frequently mixed in the same dose (generally base cocaine in Madrid and Seville, and cocaine hydrochloride in Barcelona).


CONCLUSIONS
Important geographic differences persist in the prevalence of drug injection and in the patterns of heroin and cocaine use, which could explain the unequal distribution of some health problems. The difficulties encountered in recruiting the sample suggest that the incidence of heroin use has declined considerably.
de la Fuente de Hoz
Luis
L
Secretaría del Plan Nacional sobre el Sida, Ministerio de Sanidad y Consumo, Madrid. lfuente@isciii.es
Brugal Puig
M Teresa
MT
Ballesta Gómez
Rosario
R
Bravo Poetela
María J
MJ
Barrio Anta
Gregorio
G
Domingo Salvany
Antonia
A
Silva do Rosario
Teresa
T
Ambrós Hortensi
Mireia
M
D000328:Adult; D015331:Cohort Studies; D005260:Female; D006556:Heroin Dependence / Q000453:epidemiology*; D006801:Humans; D008297:Male; D013030:Spain; D011795:Surveys and Questionnaires; D014504:Urban Health