Background: Of critical importance to AIDS control in Spain is the analysis of geographical variation and trend over time in the prevalence of intravenous administration in heroin users, as well as the factors associated with the use of this route.
Methods: We carried out a cross-sectional study of 27,655 people admitted to outpatient treatment for heroin dependence in 15 of the 17 Autonomous Communities of Spain during 1991, using data provided by the State Information System on Drug Abuse (SEIT). To assess the association of some factors with use of the intravenous route crude and logistic analysis was performed.
Results: The prevalence of intravenous administration in this population was 64.4% with regional differences ranging between 33% and 90%. Crude and logistic analysis demonstrated a strong association with two factors in addition to geography: the year of first use and the age at first use (the earlier the first use, the greater the strength of the association).
Conclusions: These findings are of paramount importance for the control of the HIV epidemic in Spain and further study in this area could help to guide policy development.