HIV seroprevalence among drug users: an analysis of selected variables based on 10 years of data collection in Porto Alegre, Brazil

Data from five studies were pooled to describe associations between drug use and HIV. The Risk Assessment. Battery in Porto Alegre, Brazil, was used to collect data from 1449 subjects in 5 separate studies conducted between 1995 and 2004. The subjects were divided into categories based on their pattern of drug use: (1) injection drug users (IDUs), (2) crack smokers, (3) frequent drug users, and (4) infrequent cocaine/alcohol/marijuana users. The sample consisted primarily of young males with low education and income levels. Half of the subjects reported frequent condom use, and exchanges involving drugs, sex, and money were infrequent (although more common in groups 1 and 2). The overall seroprevalence was 20.6%, and the prevalence was different across the four groups, showing a linear decrease from group 1 (57.1%) to group 4 (11.7%). The IDU and crack-smoking groups showed similarities in their risk levels when compared with the other two groups, and individuals in group 1, 2, and 3 were more likely to report having had four or more sex partners. After controlling for all other risk factors, IDU, males having sex with males, and crack use were highly associated with HIV (OR 7.30, 95% CI: 5.10.10.40; OR 3.04, 95%CI: 1.89,4.80; OR 2.03, 95%CI: 1.40, 2.92, respectively). The findings confirm that poverty, low education, and IDU remain risk factors for HIV in Porto Alegre, Brazil, and the study identities crack smoking as a new risk factor.