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PrEP Preferences of Gay Men Are Predicted by Frequency and Predictability of Sex

A survey from the U.S. and Canada recently published in the Journal of Acquired Immune Deficiency Syndromes reveals that, on the whole, HIV-negative gay men would rather take pre-exposure prophylaxis (PrEP) intermittently and only before they anticipate sex, in what has been called "event-driven" or "on-demand" PrEP.

[Produced in collaboration with Aidsmap.com]

The study was conducted in 2011 after the iPrEx study results came out and around the time PrEP received approval from the U.S. Food and Drug Administration, so its results were not influenced by later trial results. It was done in preparation for the ADAPT (HPTN 067) trial of 3 different PrEP regimens, the first results of which were announced at this year’s International AIDS Society Conference this summer in Vancouver.

The respondents were asked about event-driven and 2 other types of PrEP -- daily and twice-weekly dosing with an added dose after sex (sometimes called "time-driven" dosing). Although event-driven dosing remained the most popular strategy, the popularity of the other 2 was affected by how frequently participants had condomless anal sex, and whether it was usually planned or sometimes unplanned.

The Study Participants

The study was conducted online and advertised on a popular gay dating site. Of 18,710 men who clicked through to the survey from its ad, 6993 answered an initial screening questionnaire (designed to weed out HIV-positive, non-U.S./Canadian, and under age 18 enquirers), 5079 enrolled, and 3217 completed all questionnaire items.

The questionnaire asked respondents about the frequency of condomless anal sex and how much of it was "unplanned." "Planned" had quite a wide definition and included not only an arranged date, but also going to a sex party, bathhouse, or bar with the intention of having sex on the premises or that night. So "unplanned" might be better called "unexpected."

The average age of respondents was 40 years, 84% were white, 97% defined themselves as gay, and 69% were college graduates -- illustrating one of the problems of Internet surveys, namely that they tend to select whiter, richer, and better-educated people than in the general population.

Nearly half of respondents (46%) had had at least 1 experience of unplanned condomless sex in the last 3 months. 8% of respondents were classed as having "frequent" condomless sex, which was defined as having it at least once a week throughout the last 3 months.

Having unplanned sex was associated with lower education (college graduates were 32% less likely to have it), but on the contrary a higher income (men who earned more than $18,000 a year were about 30% more likely to have unplanned sex than lower-income men). Unplanned sex was also associated with identifying as gay rather than bisexual and perceiving oneself at high risk of HIV infection. It was, as one would expect, associated with generally having condomless sex often (over 5 times in the last 3 months), but also with being in a monogamous relationship. Finally, it was also associated with not having had a healthcare appointment in the last year.

Because the "frequent condomless sex" group was smaller, there were fewer clear associations with other factors, but the 8% in this group tended to be younger (1% less likely to be in this group per year older), to define themselves as gay, and to perceive themselves at higher risk for HIV. It was very strongly associated with being in a monogamous relationship: monogamous men were over 4 times more likely to be in this category than anyone else. This probably attests to the adoption of serosorting or negotiated safety agreements between long-term partners.

There were no associations between depression, drinking or drug use, and the type or frequency of sex.

The survey found that 80% of condomless anal sex was planned or expected. Interestingly, it was not the case that sex was more frequent on weekends; just 14% of respondents only, or generally, had sex on weekends. For condomless sex in general, it was most likely to happen on Thursday, Friday, or Saturday, while unplanned condomless sex happened at the same frequency throughout the week except for Sunday or Monday.

PrEP Preferences

The respondents were asked which type of PrEP regimen they felt they would prefer if they took PrEP. The most popular was event-driven PrEP, on the basis of the regimen used in ADAPT (a single dose within 48 hours before anticipated sex and another dose no more than 2 hours after sex if it happened): 76% of respondents said they would take PrEP on that basis.

In addition, 62% said they would take time-driven PrEP, which in ADAPT meant 2 regular doses a week plus a post-sex dose. 50% said they would take daily PrEP.

These results, however, were influenced by whether sex was unplanned or frequent. While intermittent PrEP remained the most popular choice, men who had frequent condomless sex were 50% more likely to also say they would take daily PrEP, while men who had experienced unplanned sex were 24% more likely to say they would take time-driven PrEP. Meanwhile, men who only had planned sex were 21% more likely to prefer event-driven PrEP than average.

The survey was conducted before the first adherence results from ADAPT were announced. This international study compared adherence among participants given daily, time-driven, or event-driven PrEP in 3 cities (gay men in Bangkok and Harlem in New York City, and women in Cape Town).

Interestingly, ADAPT found that adherence was inversely proportional to the popularity of the PrEP regimens in this preparatory study. At the trial site with the best adherence -- namely the gay men in Bangkok -- 85% of sex acts were adequately covered by daily PrEP, 84% by time-driven PrEP, but only 75% by intermittent PrEP. In Harlem, among largely poorer black gay men, 66% of acts were covered by daily PrEP, 47% by time-driven PrEP, and 52% by intermittent PrEP.

It thus appears that the anticipated ease of a PrEP regimen may not in reality be mirrored by the actual ease of taking it. 

Nonetheless, in the Ipergay study only 43% of participants took the full amount of PrEP, according to protocol, every time they had sex, and yet Ipergay demonstrated 86% effectiveness. Drug level studies conducted by the Ipergay researchers indicate that drug levels in most users of intermittent PrEP could be high enough to protect most users, as least for anal sex, as long as adherence does not fall below a certain threshold. However, Ipergay used a regimen of 2 PrEP pills before sex and 1 on each of the 2 days after, so the drug exposure was roughly twice that in ADAPT.

10/19/15

Reference

C Stack, C Oldenburg, M Mimiaga, KN Mayer, et al. Sexual Behavior Patterns and PrEP Dosing Preferences in a large sample of North American Men who have Sex with Men. Journal of Acquired Immune Deficiency Syndromes. September 11, 2015 (online ahead of print).