Prevalence of HIV infection and risk habits in heroin takers of Barcelona,Madrid and Sevilla (Spain). An example of the advantages of focusing studies on drug-takers in spite of intravenous drug users

BACKGROUND: The switch from intravenous heroin administration to smoking of heroin might be changed the trends in the prevalence of HIV infection and risk behaviours among Spanish users. SUBJECTS AND METHODS: Cross-sectional study of 909 regular heroin users, re cruited within and outside of drug treatment centres. The prevalence of HIV infection and risk behaviours were studied in the whole sample and among i njectors. RESULTS: The proportion of heroin users who had ever injected was 86.7% in Barcelona, 71.1% in Madrid and 56.1% in Seville, while the proportion of th ose who had injected in the last 30 days was 79.7, 35.6 and 29.2%, respecti vely. The prevalence of HIV infection among users who had ever injected was 46.2% in Barcelona, 39.6% in Madrid and 47.1% in Seville; in the total pop ulation of heroin users the prevalence was 40, 31.1 and 28%, respectively. Among current injectors, 10.9% in Barcelona, 13.9% in Madrid and 23.6% in S eville reported they had injected with used syringes in the last 30 days, w hile the corresponding proportion among the total population of users was 8 .7, 4.9 and 6.9%, respectively. Moreover, 19.2% of injectors in Barcelona, 16.7% in Madrid and 16.9% in Seville admitted to injecting drugs which had been diluted in syringes previously used by others in the last 30 days; of this group, over half stated they had not injected with used syringes durin g that period. CONCLUSIONS: The prevalence of HIV infection and risk behaviours among hero in users differs depending on whether all users or only injectors are consi dered. This suggests that the transition from injecting to smoking is one o f the major factors contributing to the control of the HIV epidemic in Spai n. This contribution, which has little to do with regional prevention polic ies, must be taken into account when comparing their effectiveness.