PROUD pilot study interim analysis finds pre-exposure prophylaxis (PrEP) is highly protective against HIV

Today’s announcement that all participants in the PROUD pilot study, which investigates a number of questions surrounding the use of PrEP by gay men, will be offered PrEP is both a source of relief and concern.

Relief, because we knew that PrEP works before the start of the study, but we also knew that its effectiveness very much depends on users taking the drug as prescribed. There was a risk that, as had happened in a couple of previous studies, participants would not adhere to a daily regimen or would change their behaviour to such extent that this would cancel the protective effect of taking PrEP.

The observation that the effectiveness seen in the study has exceeded the threshold set for trial continuation suggests a high level of adherence to the daily PrEP regimen by the participants, which were identified at high risk of infection, and therefore that PrEP can make a difference at individual level in this group.

Concerns because this may still not be good enough for the health commissioners to allow the use of Truvada (the drug used in study) for the prevention of HIV in gay men in the UK. And concerns about the ongoing provision of Truvada to the participants as they exit the study.

The future of the larger PROUD study which aimed to enroll a further 1,800 men into the trial from January 2015 is also in the balance. The results of the interim analysis and the recommendation of the Trial Steering Committee to offer PrEP to participants that were on the deferred arms is challenging the design of this trial and other studies.

The PROUD pilot study with its immediate/differed design was not set up to establish the effectiveness of PrEP, which would have been established with the larger PROUD study, but this is no longer a feasible or justifiable option.

As noted by the PROUD Study Team, there are still a number of outstanding questions about real-life effectiveness (and population-level effectiveness) and the costs of implementing PrEP in the UK:

  • Does PrEP reduce HIV, taking account of changes in risk behaviour and adherence?
  • Are most-at-risk UK MSM interested in PrEP as additional protection against HIV?
  • Will they take the tablets regularly enough to protect themselves?
  • What effect will taking PrEP have on their sexual risk behaviour?
  • Will resistance be a big problem in any breakthrough HIV infections?
  • Will PrEP be cost-effective in the UK?

Though legitimate the question for me as always been how these should be answered, that is with a clinical trial or through implementation projects? With a growing number of studies  demonstrating that PrEP works when taken as directed, the scientific and ethical ground to conduct either immediate/deferred study like PROUD or a placebo study like Ipergay is becoming untenable.

This results could be a major step forward to make PrEP a reality in the UK (and elsewhere) as it is in the US. Today, the economic context and the political will are the last two obstacles in the path to make a new prevention option available to gay men in the UK where they still account for half of new infections year on year.

We are standing on the verge of making a potentially huge step forward in the field of HIV prevention and our ability to bring down the epidemic. We just need a little push that could come from PrEP users and all those who believe that gay men deserve the right to access an HIV prevention which we know work.


See also: High effectiveness seen in English PrEP trial by Gus Cairns, Aidsmap.

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