This abstract was presented as a poster at the 11th Annual Canadian Conference on HIV/AIDS Research in Winnipeg in April 2002.

Distinct risk profiles of injection drug using men who have sex with men 
(IDU/MSM) in two prospective cohorts in Vancouver

Keith Chan, Kathy Li, Amy E. Weber, Steve Martindale, Mary Lou Miller, Robert S. Hogg.

The Vanguard Project and VIDUS, BC Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, BC.

OBJECTIVES:

To compare IDU/MSM in a prospective cohort of young MSM (Vanguard); and a cohort of IDUs (VIDUS).

METHOD:

We identified 92 Vanguard participants who had injected drugs in the past year, and 72 male VIDUS participants who had had sex with men in the past six months. Those in both cohorts were excluded. Contingency tables and non-parametric methods were used to compare sociodemographics, substance use and sexual behaviors between the two groups.

RESULTS:

Compared to IDUs in Vanguard, MSM in VIDUS were older (median: 30 vs. 23 years, p<0.001) and more likely to have graduated from high school (75% vs.49%, p=0.001).

VIDUS participants were also more likely to have ever been sexually assaulted (54% vs. 37%, p=0.040), to have used dirty needles (56% vs. 39%, p=0.040), injected drugs daily (57% vs. 35%, p=0.005), injected cocaine (90% vs. 65%, p<0.001), and have a higher CESD depression score (median: 17 vs. 11, p<0.001).

Vanguard IDUs were more likely to have used various drugs in the past year, including marijuana (85% vs. 64%, p=0.004), crack (65% vs. 22%, p<0.001), speed (37% vs. 17%, p=0.005) and acid (50% vs. 18%, p<0.001). They also had a higher sexual risk profile, characterized by unprotected receptive (43% vs. 21%, p=0.003) and insertive anal sex (38% vs. 15%, p=0.002) with either regular or casual partners.

CONCLUSIONS:

Significant differences were found between these two groups of IDU/MSM. Those in the IDU cohort were older, better educated, more likely to have been sexually assaulted, shared needles, inject daily and be depressed. Participants in the MSM cohort were more likely to use a variety of drugs and to have greater sexual risk of HIV transmission.

The distinct risk profiles of these two groups suggest diversity within both the IDU and MSM populations, which should be incorporated into prevention efforts.