PrEP acceptable to gay men and few report that it would change their risk behaviour

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Approximately 50% of American gay men said they were likely to use pre-exposure prophylaxis (PrEP), but few reported that it would lead to a change in their risk behaviour, according to data presented to the International AIDS Society conference in Rome.

Nevertheless, the investigators were concerned that even minor increases in rates of unprotected anal sex could offset the benefits of pre-exposure prophylaxis.

The IPrEX study showed that PrEP significantly reduced the risk of infection with HIV for gay and bisexual men. Overall, men who took PrEP had their risk of HIV reduced by 44%. If adherence was high, the risk was reduced by 73%.


risky behaviour

In HIV, refers to any behaviour or action that increases an individual’s probability of acquiring or transmitting HIV, such as having unprotected sex, having multiple partners or sharing drug injection equipment.

Ryan White HIV/AIDS Program

In the United States, the largest federally funded programme providing HIV-related services to low-income, uninsured, and underinsured people with HIV/AIDS.

odds ratio

Comparing one group with another, expresses differences in the odds of something happening. An odds ratio above 1 means something is more likely to happen in the group of interest; an odds ratio below 1 means it is less likely to happen. Similar to ‘relative risk’. 


Insertive anal intercourse refers to the act of penetration during anal intercourse. The insertive partner is the ‘top’. 


Receptive anal intercourse refers to the act of being penetrated during anal intercourse. The receptive partner is the ‘bottom’.

“PrEP offers much promise as the first biomedical intervention to have success in at-risk men who have sex with men,” comment the researchers.

They therefore undertook further analysis to see how likely the men who participated in the study were to use PrEP and if its availability would change their HIV risk behaviour.

They undertook a survey in December 2010, immediately following the release of the IPrEX results, using Facebook and Black Gay Chat to recruit participants. A total of 1155 gay and other men who have sex with men were recruited to the study.

Participants completed a questionnaire about their knowledge and willingness to use PrEP; perceptions of the risk of HIV infection from unprotected anal sex with or without PrEP; perceptions of sexual pleasure; and perception of likelihood to experience sexual pleasure with or without a condom and with or without PrEP.

The men had an average age of 33 years, 75% were white, and 51% reported unprotected anal sex at least once in the last twelve months.

Only a third of men had heard of PrEP before the release of the study results. Just under half of individuals reported that they were “very” or “extremely” likely to use PrEP.

Unprotected anal sex without a condom was widely considered to involve a high risk of HIV.

The availability of PrEP did not alter the perception of the risk associated with HIV in the majority of men, regardless of whether they were the insertive (75%) or receptive (60%) partner in anal sex.

Three-quarters of men stated that the 44% efficacy of PrEP in the IPrEX study would not affect their use of condoms. However, 7% reported that they would use condoms less frequently.

Unprotected anal sex without a condom was perceived as very pleasurable by approximately 50% of respondents.

Most men reported that the availability of PrEP would not affect either pleasure from unprotected sex, or the pressure to have unprotected sex.

However, 30% of men believed that PrEP would mean that there would be increased pressure to have unprotected sex.

A number of factors were associated with an increased willingness to use PrEP. These included:

  • A belief that PrEP reduced the risk of infection with HIV (adjusted odds ratio [AOR] = 1.40; 95% CI, 1.17-1.67, p < 0.001).

  • Increased pleasure from unprotected anal sex (AOR = 1.13; 95% CI, 1.02-1.26, p = 0.023).
  • Increased pressure to have anal sex without a condom (AOR = 1.22; 95% CI, 1.10-1.35, p < 0.001).

The investigators were generally encouraged by these results, and concluded “providing education and accurate messaging around PrEP may help increase uptake and reduce risk compensation”.


Irvin R et al. Risk compensation and pre-exposure prophylaxis (PrEP): a post-iPrEX survey of men who have sex with men (MSM). Sixth International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention, Rome, abstract TUAC0104, 2011.

View abstract TUAC04 on the conference website