This poster was presented at the 10th Annual Canadian Conference on HIV/AIDS Research in Toronto in June 2001 and at the AIDS Impact conference in Brighton, England, in July 2001.

Increasing rate of new HIV infections among young gay and bisexual men in Vancouver, 1995-99 vs. 2000

Steve Martindale, Kevin JP Craib, Keith Chan, Mary Lou Miller, Darrel Cook*, Robert S. Hogg.

The Vanguard Project, BC Centre for Excellence in HIV/AIDS, Vancouver, BC, Canada.
* BC Centre for Disease Control, Vancouver, BC, Canada.

OBJECTIVES:

To determine changes in the incidence of HIV among young gay and bisexual men in an open cohort.

METHODS:

Since May 1995, young gay and bisexual men aged 15 to 30 have been recruited into an ongoing prospective study of HIV incidence and risk behaviors in the Greater Vancouver region.

Among men who had returned for follow-up, HIV incidence was calculated using person-time methods. Ninety-five percent confidence intervals (95%CI) were calculated based on the Poisson distribution.

RESULTS:

As of December 31, 2000, 668 participants had completed at least one follow-up visit and more than one HIV test.

Table 1 provides a summary of HIV incidence in the cohort by year since its inception in 1995.

A total of 26 HIV infections were prospectively observed. The overall HIV incidence rate in the cohort was 1.4 per 100 person-years (95%CI: 0.8-1.9).

Participants who reported ever injecting drugs had a higher overall incidence rate (3.9 per 100 person-years; 95%CI: 1.0-6.8) than those who did not (1.0 per 100 person-years; 95%CI: 0.5-1.4).

As illustrated in Graph 1, a significant increase in new HIV infections was observed between 1995/99 and 2000 within the entire cohort; this remained true when participants who had ever injected drugs were excluded from the analysis (p<0.05).

Among men who have never injected drugs, the rate of new infections has increased from 0.6 per 100 person years in 1995-99 (95%CI: 0.2-1.0) to 3.7 per 100 person years in the year 2000 (95%CI: 1.0-6.5).

CONCLUSIONS:

Our data indicate a recent significant increase in the rate of new HIV infections in young gay and bisexual men in the Vancouver area. Among non-injection drug using participants we observed a six-fold increase in infection rates over the past year.

These results corroborate previous reports from other large North American cities, suggesting the need for continued surveillance and further investigation of the determinants of seroconversion in order to assist with the efforts to stabilize or decrease seroincidence in this population.

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