Sexual role versatility among HIV-negative US MSM contributing to high level of HIV incidence

Versatility in anal sex roles is a likely explanation for the continued high rate of new HIV transmissions among men who have sex with men (MSM) in the United States, results of a study published in the online edition of the Journal of Acquired Immune Deficiency Syndromes suggest.

Investigators found that almost two-thirds of HIV-negative MSM engaging in unprotected anal sex were sexually versatile, adopting both the insertive and receptive positions.

“Versatile men at high infection risk via receptive UAS [unprotected anal sex] are likely to transmit HIV via insertive UAS,” comment the authors. The results also showed that only 17% of men were exclusively insertive, suggesting that circumcision would have little impact on the course of the HIV epidemic among US MSM.

Over half of new HIV infections in the United States are among gay and other MSM. Almost all the HIV infections in this population are due to unprotected anal intercourse, and the risk of infection with HIV is especially high for men who adopt the receptive role during unprotected anal sex.

Little is known about anal sex position among high-risk MSM in the United States.

Investigators from the EXPLORE study therefore examined data obtained from over 2500 HIV-negative men reporting unprotected anal sex. Participants were recruited between 1999 and 2001 and followed for an average of 3.25. Every six months, individuals were asked which role they had adopted during unprotected anal sex: exclusively insertive; exclusively receptive; or both (versatile). The investigators conducted a series of analyses to see if there were any factors associated with role and position during unprotected anal intercourse.

The men had a mean age of 34 years, three-quarters were white and two-thirds had a college degree. Non-injection drug use – including poppers – was highly prevalent and reported by 65% of participants.

Overall, 63% of men reported that they were versatile and had both insertive and receptive unprotected anal sex. These versatile men reported a median of eight unprotected anal sex episodes in each six-month period.

Only 17% of men said they were exclusively insertive. Exclusively insertive men reported a median of one unprotected anal sex act per six-month period. The remaining 10% of men said they were exclusively receptive, and they also reported a median of one episode of unprotected sex per six months.

Analysis focused on the 70% of study visits where unprotected anal sex was reported.

Unprotected sex with an HIV-negative partner was reported at 9000 of these visits; with a man of unknown status at 5924 of visits; and with an HIV-positive partner was reported at 1980 visits.

For visits with unprotected anal sex, 20% were classified as exclusively receptive, 31% as exclusively insertive and 49% as versatile.

The HIV status of partners appeared to influence sexual positioning. With HIV-positive partners, 54% of reported episodes of unprotected sex were exclusively insertive. A similar proportion of instances of unprotected anal sex with HIV-negative partners were versatile. With partners of unknown status, the most prevalent role was exclusively insertive (46%).

Individuals were 50% more likely to report being exclusively insertive when they did not know the HIV status of their partner (aRRR = 1.51; 95% CI, 1.29-1.77, p < 0.0001). The odds of being exclusively insertive increased by a factor of two and a half when the partner was known to be HIV positive (aRRR = 2.34; 95% CI, 1.98-2.75, p < 0.0001).

Being exclusively receptive compared to being exclusively insertive was more likely among men reporting the use of poppers (aRRR = 1.21; 95% CI, 1.05-1.41, p =0.01). Men aged 25 and younger were the age group most likely to report being exclusively receptive. The odds of this decreased with age and were lowest for those aged 36 and older (p < 0.0001).

“Our finding that exclusively receptive men during UAS tended to be younger might be contributing to the rising HIV incidence in young MSM in the US,” suggest the investigators.

Versatility was associated with the HIV status of partners. Participants were 34% more likely to report being exclusively insertive with a man whose HIV status they did not known and 3.5 times more likely with HIV-negative compared to HIV-positive partners.

Men were significantly less likely to be versatile compared to exclusively insertive is they were older or black. Versatility was positively associated with sex with a regular partner and use of several substances, including poppers, amphetamines and hallucinogens.

“Almost two-thirds of men reported both insertive and receptive positions…with only a small proportion remaining exclusively insertive or receptive,” comment the authors, who note “several modeling studies proposed that greater role versatility could promote HIV transmission”. They believe their results underline the importance of “examining anal sex role patterns in understanding factors driving the HIV epidemic among MSM”.