There is a powerful link between substance use among HIV-negative gay men and high-risk sex, especially when numerous substances are involved before or during sex, aidsmap reports. Publishing their findings in the online edition of the Journal of Acquired Immune Deficiency Syndromes, researchers from Project ECHO in San Francisco studied 3,173 HIV-negative gay men in San Francisco between 2009 and 2012, conducting a telephone interview with the participants about their use of drugs and alcohol and their sexual risk taking.

The investigators categorized the participants’ use of cocaine, methamphetamine and poppers in terms of whether they used substances episodically—defined as less than once a week, or weekly—or more often than weekly. The study defined as heavy drinkers those who consumed an average of more than four drinks each day, while those who drank less were considered moderate drinkers.

Forty-five percent of the participants reported unprotected anal sex, and one in four reported high-risk sex, defined as unprotected sex with a partner who was either HIV positive or had an unknown HIV status.

Those who used methamphetamine and cocaine episodically were a respective 3.31 and 1.86 times more likely to have high-risk sex when compared with non-users. For more frequent users of these substances, there was a respective 5.46- and 3.13-fold increase in likelihood of high-risk sex. Episodic and more frequent users of poppers had a respective 2.08- and 2.54-fold increase in likelihood of high-risk sex when compared with non-users. And heavy drinkers had a 1.90-fold increase in likelihood of sex with a partner who was HIV positive or had an unknown HIV status.

The number of substances used before or during sex had a very strong influence on the likelihood of high-risk sex. If one substance was used, the increased likelihood was 16.81-fold, if two it was 27.31-fold, and if three or more it was 46.38-fold.

To read the aidsmap story, click here.

To read the study abstract, click here.