PrEP: a new prevention tool?

So far, PrEP is considered an experimental prevention method. Currently, no antiretroviral drug is approved for use as PrEP but studies indicate it could be a useful prevention tool for people at high risk of HIV infection, including gay men who have unprotected sex with multiple partners, whose partners have multiple partners, or who are in a relationship with someone with HIV (recent research in the US found young gay men in relationships they considered 'serious' were eight times more likely to have unprotected sex).

Research into PrEP so far has had mixed results. Some recent studies have had promising findings. In iPrEx trial of Truvada as PrEP in gay men, efficacy was 44%, meaning that there were only just over half as many infections in men who took PrEP as in those who didn't. It was 92% effective in men who took their drugs every day. However only half the study participants took their drugs at all, suggesting that, for PrEP to be an effective prevention strategy, it should only be offered to those highly motivated to take it.

In a follow-up to the iPrEx study, gay men said they would be willing to use PrEP and, importantly, that using it would not result in an increase in higher-risk behavior. Even a relatively small increase in current rates of unprotected anal sex in PrEP users could result in more rather than fewer infections. Even if it doesn’t, because of the cost of providing anti-HIV drugs as PrEP, it might make it unaffordable.

A study conducted in the US found that the majority of gay men would want PrEP to provide near-perfect levels of protection before they would consider it a replacement for condom use, but the minority of men who had difficulty negotiating safer sex thought they might consider PrEP instead of condoms even if it were only about 50% effective. The researchers suggest it would be important to combine other interventions, such as counselling about reducing risk behaviour with the availability of PrEP.

In the UK, where infection rates in gay men are starting to rise again, the Health Protection Agency (HPA) has proposed a radical change to HIV prevention for gay men at the highest risk of HIV. The proposed Intensive Combination Prevention (ICP) programme includes a standardised tool that patients can use to assess their level of HIV risk, regular appointments for HIV and STI testing, and enhanced safer-sex counselling. It will also include a trial of PrEP, comparing the HIV infection rate in men who are offered PrEP immediately with the rate in men who delay taking it till later. The HPA and its partners are taking a pilot study forward, and have just applied for funding for a large study.

BHIVA, along with BASHH, the UK’s association of GUM doctors, are currently preparing a position statement on the use of PrEP in the UK.