The use of poppers, stimulant drugs such as cocaine, and erectile dysfunction drugs, significantly increases the risk of HIV infection for gay men, especially when used together, according to an article published in the online edition of the Journal of Acquired Immune Deficiency Syndromes. “It is increasingly clear that combination sex drug usage contributes significantly to the spread of HIV infection among vulnerable MSM [men who have sex with men]”, comment the investigators.
There is accumulating evidence that the use of inhaled nitrites (poppers), stimulant drugs (cocaine, ecstasy and amphetamines) and erectile dysfunction drugs such as Viagra are associated with an increased risk of new HIV infections in gay men.
Investigators from the large Multicenter AIDS Cohort Study (MACS) wished to determine the effect of the use of poppers, stimulants and erectile dysfunction drugs in combination on the risk of HIV seroconversion. Their analysis covered a ten-year period between 1998 and 2008 and included 1667 men who were HIV-negative at baseline. Every six months, the men were tested for HIV and interviewed about their sexual and drug-taking behaviours.
During the period of the study, 57 men became infected with HIV.
Just over a fifth (22%) of the men who acquired HIV, reported receptive unprotected anal intercourse with two or more men in the previous six months, compared to only 5% of men who remained HIV-negative.
The use of poppers and erectile dysfunction drugs, either alone or together, was more common amongst men who were diagnosed with HIV during the study than HIV-negative men (33% vs 23%).
Similarly, stimulant use, together or in combination with poppers or erectile dysfunction drugs, was also more prevalent amongst men who became infected with HIV during the course of the study (33% vs 16%) than amongst men remaining HIV-negative.
Statistical analysis that controlled for potentially confounding factors was then performed. This showed that the more men an individual had unprotected receptive anal sex with, the greater their risk of acquiring HIV (two to four men, hazard ratio [HR] = 4.23, 95% CI = 1.76-10.17; five or more men, HR = 14.21, 95% CI = 6.27-32.20).
Significant associations were also found between the risk of seroconversion and the use of stimulants (HR = 2.99, 95% CI = 1.02-8.76). The use of poppers, alone or in combination with other drugs, was also significantly associated with acquiring HIV infection (HR = 3.89, 95% CI = 1.53-8.76), as was the use of erectile dysfunction drugs (HR = 3.44, 95% CI = 1.03-11.53).
The greatest risk of infection with HIV was seen in men who reported use of all three types of drugs – stimulants, poppers and erectile dysfunction drugs (HR = 8.45, 95% CI = 2.67-26.71).
Next the investigators conducted an analysis to establish the contribution that individual or combined risk factors made to the risk of acquiring HIV. The investigators calculated that 63% of HIV infections seen during the period of their study were associated with drug use. They found that 74% of infections could be attributed to unprotected anal intercourse and drug use. However, only 41% of the risk was directly attributable to unprotected receptive anal intercourse, meaning that a third of the risk of acquiring HIV was due to the use of poppers, stimulants or erectile dysfunction drugs alone or in combination.
“Noninjection substance use that commonly accompanies unprotected anal sex with multiple partners remains a potent predictor of HIV seroconversion among men who have sex with men…the time seems long past to design and evaluate interventions that will disentangle the conjoined epidemics of substance use and high-risk sex in this population”, conclude the investigators.
Ostrow DG et al. Specific sex drug combinations contribute to the majority of recent HIV seroconversions among MSM in the MACS. J Acquir Immune Defic Syndr (online edition), 2009.