Most of the participants in the IPERGAY trial of a intercourse-based Truvada (tenofovir/emtricitabine) as pre-exposure prophylaxis (PrEP) dosing protocol had high levels of PrEP, condoms, or both, aidsmap reports. Meanwhile, about one sixth of the participants had low levels of protection from either method. Additionally, evidence suggested that, among those who began the trial with relatively high condom use rates, their latex use tended to decline during the trial.

The placebo-controlled IPERGAY study began in February 2012 and included 414 high-risk HIV-negative MSM in France and one in Canada. The participants were randomly assigned to receive either Truvada or a placebo. They were instructed to take two doses of the drug between 24 and two hours before intercourse (or one pill, if the most recent dose was taken between one and six days before), and then, if intercourse did occur, to take one dose every 24 hours after that first dose, until they had taken two pills since the last time they had anal sex.

After the randomized phase of the study was stopped early in October 2014, the researchers found that the dosing protocol reduced the risk of HIV by 86 percent. However, because the men were taking an average of about four tablets of Truvada per week, a level of use that other research has found confers maximum protection against the virus, it is still not clear whether the dosing protocol itself was responsible for the considerable reduction in risk.

In this new substudy of the IPERGAY trial, researchers looked at 332 participants, all men who have sex with men (MSM) who had anal sex at least once during the study follow-up period and who provided information on PrEP or condom use, or on both, for their most recent sex act. A total of 47.9 percent of these men received the placebo and 52.1 percent received Truvada.

Results were presented at the 2016 Conference on Retroviruses and Opportunistic Infections (CROI) in Boston.

Almost 40 percent of the participants in the substudy reported that they used PrEP consistently, covering 95 to 100 percent of most-recent sex acts. Thirty-one percent of participants used PrEP at high rates, but inconsistently, covering 70 to 90 percent of most-recent sex acts. Sixteen percent of participants reported using PrEP for their most recent sex acts only occasionally. During the first two months of the trial, the men in this last category reported 90 percent PrEP coverage, but by the 10th month this rate had dropped to 50 percent. The rate rose slightly at the one-year mark and then fell close to zero by month 16.

Seventy percent of the men used condoms at low rates, reporting using them for their most-recent sex act 10 to 25 percent of the time throughout the trial. The remaining 30 percent of participants used condoms at a relatively high rate, but with high variability: their rate of condom use for their most recent sex act ranged between 45 percent and 80 percent during the study. The condom use among this latter group tended to decline during the study: from a rate of 78 percent one month into the trial to 45 percent after 18 months; although the rate increased again to 71 percent by the 24-month mark.

The cross-section of condom and PrEP use rates among the men were as follows: 54 percent of the men used PrEP consistently or at relatively high rates while not using condoms often; 23.5 percent used both PrEP and condoms at relatively high levels; 6.5 percent used condoms at relatively high rates but rarely used PrEP; and 16 percent rarely used PrEP or condoms.

Compared with those who used PrEP and condoms at relatively high levels, those who rarely used either form of HIV protection tended to be older (for every 10 years of additional age, they were 50 percent more likely to fall into this low-protection category). Those men who rarely used condoms or PrEP were also twice as likely to not have a college education, twice as likely to report dissatisfaction with their sex lives, and were almost three times more likely to report having sex with strangers. These men were also somewhat more likely to report being the active member (the top) during anal sex.

To read the aidsmap article, click here.

To read the conference abstract, click here.