Pubdate: Tue, 07 Jan 2003 Source: Canadian Medical Association Journal (Canada) Copyright: 2003 Canadian Medical Association Contact: http://www.cmaj.ca/ Details: http://www.mapinc.org/media/754 Authors: Kevin J.P. Craib, Patricia M. Spittal, Evan Wood, Nancy Laliberte, Robert S. Hogg, Kathy Li, Katherine Heath, Mark W. Tyndall, Michael V. O'Shaughnessy and Martin T. Schechter RISK FACTORS FOR ELEVATED HIV INCIDENCE AMONG ABORIGINAL INJECTION DRUG USERS IN VANCOUVER From the British Columbia Centre for Excellence in HIV/AIDS, St. Paul's Hospital (all authors), and the Departments of Health Care and Epidemiology (Craib, Spittal, Wood, Hogg, Heath, Tyndall and Schechter) and of Pathology and Laboratory Medicine (O'Shaughnessy), University of British Columbia, Vancouver, BC. Correspondence to: Dr. Patricia Spittal, BC Centre for Excellence in HIV/AIDS, St. Paul's Hospital, 608-1081 Burrard St., Vancouver BC V6Z 1Y6; fax 604 806-9044; Abstract Background: Because of established links between entrenched poverty and risk of HIV infection, there have long been warnings that HIV/AIDS will disproportionately affect Aboriginal people in Canada. We compared HIV incidence rates among Aboriginal and non-Aboriginal injection drug users (IDUs) in Vancouver and studied factors associated with HIV seroconversion among Aboriginal participants. Methods: This analysis was based on 941 participants (230 Aboriginal people) recruited between May 1996 and December 2000 who were seronegative at enrolment and had completed at least one follow-up visit. Incidence rates were calculated using the Kaplan-Meier method. The Cox proportional hazards regression model was used to identify independent predictors of time to HIV seroconversion among female and male Aboriginal IDUs. Results: As of May 31, 2001, seroconversion had occurred in 112 (11.9%) of the participants, yielding a cumulative incidence of HIV infection at 42 months of 12.7% (95% confidence interval [CI] 10.3%-15.1%). The cumulative incidence at 42 months was significantly higher among the Aboriginal participants than among the non-Aboriginal participants (21.1% v. 10.7%, p ( 0.001). This elevation in risk was present in both female and male Aboriginal IDUs. Among the female Aboriginal IDUs, frequent speedball (combined cocaine and heroin) injection (adjusted relative risk [RR] 3.1; 95% CI 1.4-7.1) and going on binges of injection drug use (adjusted RR 2.3; 95% CI 1.0-5.2) were found to be independent predictors of HIV seroconversion. Among the male Aboriginal IDUs, the independent predictors of seroconversion were frequent speedball injection (adjusted RR 2.9; 95% CI 1.0-8.5) and frequent cocaine injection (adjusted RR 2.5; 95% CI 1.0-6.5). Interpretation: In Vancouver, Aboriginal IDUs are becoming HIV positive at twice the rate of non-Aboriginal IDUs. Our findings emphasize the urgent need for an appropriate and effective public health strategy -- planned and implemented in partnership with Aboriginal AIDS service organizations and the Aboriginal community -- to reduce the harms of injection drug use in this population. -------------------------------------------------------------------------------- Little is known about the extent of the HIV epidemic among Aboriginal people in North America., The reasons for this include limited HIV/AIDS surveillance data, underreporting, and inconsistent documentation of ethnic status between provinces. However, because of the established links between entrenched poverty and risk of HIV infection, there have long been warnings that HIV/AIDS will increasingly affect Aboriginal people in Canada.,, Regrettably, with the few data available, alarming trends have already emerged. In 1990 an estimated 1% of all reported AIDS cases involved Aboriginal people; by 1999 this proportion had increased to 10.8%. Despite constituting only about 2.8% of the general population, Aboriginal people accounted for about 9% of all people with newly diagnosed HIV infection in 1999. Indeed, from 1996 to 1999 the estimated number of Aboriginal people with HIV infection rose from 1430 to 2740. In addition, there are some data to suggest that HIV/ AIDS among Aboriginal people is disproportionately affecting youth and women. In provinces with reported ethnicity data, 33% of Aboriginal people with HIV infection newly diagnosed between 1988 and 2000 were less than 30 years old, as compared with 20% of non-Aboriginal people with newly diagnosed HIV infection; a similar difference was observed in cases involving women (47% v. 20%). With the exception of national statistics indicating that injection drug use accounted for the majority (60%) of new infections among Aboriginal people between 1998 and 2000, risk factors that explain elevated risk and transmission of HIV among Aboriginal people are not well understood. We have been following a cohort of more than 1400 injection drug users (IDUs) in Vancouver since 1996, of whom about 25% are Aboriginal people. At enrolment, HIV prevalence rates among Aboriginal IDUs were higher than their non-Aboriginal counterparts (31% v. 18%; p ( 0.001). Follow-up of the cohort now allows for an investigation aimed at comparing HIV incidence among Aboriginal and non-aboriginal IDUs and identifying predictors of HIV seroconversion among Aboriginal women and men in the study. Methods The Vancouver Injection Drug User Study (VIDUS) is a prospective study involving 1437 people who were recruited through self-referral and street outreach from Vancouver's Downtown Eastside between May 1996 and December 2000. Individuals were eligible if they were 14 years of age or older, had injected illicit drugs at least once during the month before enrolment, resided in the greater Vancouver region and provided written informed consent. Participants were given a stipend (Can$20) at each study visit to compensate them for their time and to facilitate transportation. The study was approved by the University of British Columbia/Providence Healthcare Research Ethics Board. At enrolment and semi-annually, participants completed an interviewer-administered questionnaire to elicit sociodemographic data and data on injection and non-injection drug use, injection practices and sexual risk behaviours. 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