Nitrite inhalant use among young gay and bisexual men in Vancouver during a period of increasing HIV incidence

Background: Nitrite inhalants ("poppers") are peripheral vasodilators which, since the beginning of the epidemic, have been known to increase risk for acquiring HIV infection among men who have sex with men (MSM). However, few studies in recent years have characterized use. From 1999 to 2004, new HIV diagnoses among MSM in British Columbia increased 78%, prompting us to examine the prevalence and correlates of this modifiable HIV risk factor. Methods: Self-administered questionnaires were completed between October 2002 and May 2004 as part of an open cohort study of HIV-seronegative young MSM. We measured nitrite inhalant use during the previous year and use during sexual encounters with casual partners specifically. Correlates of use were identified using odds ratios. Results: Among 354 MSM surveyed, 31.6% reported any use during the previous year. Nitrite inhalant use during sexual encounters was reported by 22.9% of men and was strongly associated with having casual partners, with greater numbers of casual partners (including those with positive or unknown serostatus) and with anal intercourse with casual partners. Nitrite inhalant use was not associated with non-use of condoms with casual sexual partners per se. Conclusion: Contemporary use of nitrite inhalants amongst young MSM is common and a strong indicator of anal intercourse with casual sexual partners. Since use appears to increase the probability of infection following exposure to HIV, efforts to reduce the use of nitrite inhalants among MSM should be a very high priority among HIV prevention strategies.