Pre-exposure prophylaxis (PrEP) would be an acceptable HIV prevention strategy for large numbers of gay, bisexual and other men who have sex with men in major UK cities, according to two studies presented to the British HIV Association (BHIVA) conference in Birmingham this week.
The conference also heard details of a small pilot PrEP study, likely to start recruiting later this year.
A cross-sectional survey of 842 HIV-negative gay and bisexual men, recruited at bars, clubs and saunas in London, suggested that half the respondents would be interested in taking PrEP.
Respondents were given information about pre-exposure prophylaxis and asked: “If PrEP were available, how likely is it that you would take a pill (oral dose) on a daily basis to prevent HIV infection?”.
Half said yes, with 16% saying they were likely to take PrEP and 34% saying they were very likely to. Men interested in PrEP were slightly more likely to be under the age of 35 (AOR adjusted odds ratio 1.58), have attended a sexual health clinic in the past year (AOR 1.59) and to have previously taken post-exposure prophylaxis (PEP) (AOR 1.96). After statistical adjustment, various measures of risky sex were no longer associated with interest in PrEP.
In this survey, 17 men (2.1% of those answering the question) said that they had previously taken antiretroviral drugs to reduce their risk of HIV infection.
Secondly, clinicians at the Manchester Centre for Sexual Health surveyed HIV-negative men attending their service who reported unprotected receptive anal intercourse. Of the 121 men who responded, 36% said they would be “very willing” to take PrEP while only 14% said they would not take the treatment. Daily dosing was perceived as a better option by four fifths of respondents – just one fifth would prefer taking a dose before sexual activity.
These data confirm and reinforce findings from a study reported in November 2011, which found that half the gay men surveyed would consider taking PrEP. Once again, daily dosing was preferred to taking a dose before sex. In the qualitative data, men commented that sex is often spontaneous and that they felt daily dosing would facilitate adherence.
However these data are all based on giving men a few key facts about PrEP and presenting it as a hypothetical option. In real-life circumstances, where men think more seriously about PrEP as an option and hear friends’ experience of taking it, actual uptake and sustainability may be very different.
While the Manchester respondents largely assured the researchers that they would take all their doses of PrEP and wouldn’t have more risky sex, real-life experience needs to be tested in research.
To this end, the Medical Research Council are seeking funding for a 5000-participant, two-year study which would randomise HIV-negative gay men who report unprotected anal intercourse to either take PrEP (Truvada) and attend motivational interviewing (intervention group) or to be put on a one-year waiting list for PrEP and to have motivational interviewing in the meantime (control group).
For the researchers, it is crucial that this is an open label but randomised study, in which participants know whether they are receiving the actual drug. This unusual research design would, they argue, tell us more about the real-world effectiveness of PrEP than a blinded study as it would take into account the possible impact of participants taking more sexual risks because they felt that PrEP afforded some protection. (Researchers call this ‘risk compensation’ or ‘behavioural disinhibition’).
Rather than test efficacy in artificial conditions, the study would therefore test effectiveness in more realistic UK conditions.
So far, however, the potential funders of this costly study have not been persuaded by this argument and it is unclear whether the study will be able to go ahead.
What will, however, start recruiting later this year is a pilot version of the same study, aiming to include 500 men who attend one of around twelve sexual health clinics.
As well as allowing the researchers to have a dry run of the main trial and identify teething problems with its strategy, it should also provide valuable information on the number of men who actually follow through on a clinician’s offer of PrEP. Data on the characteristics of men who seek PrEP, drop-out rates and risk compensation will also be collected.
The researchers intend to take some of these data back to the main study’s potential funders, in order to support a revised application.