HIV drugs protect high-risk groups

HIV drugs are effective at protecting people at high risk of contracting HIV, a new analysis concludes.

Antiretroviral therapy (ART) is beginning to be used as a preventative measure in people at high risk of acquiring the disease from sexual partners. When used in this way it is called pre-exposure prophylaxis, or PrEP.

It is often seen as controversial because of the potential for developing drug resistance, and the serious side-effects which include kidney toxicity and bone density loss. Others fear that it might encourage people to take more risks, exposing them to a higher overall chance of HIV infection.

So Dr Charles Okwundu of the University in Tygerberg, South Africa, and colleagues set out to establish how well PrEP really works.

They took figures from six trials involving 9,849 people. Participants included men who have sex with men, partners of HIV-infected people, sex workers and people who have multiple sexual partners. All received either the oral antiretroviral drug tenofovir disoproxil fumarate with or without emtricitabine taken daily, or placebo, or intermittent use of the drugs.

This showed that tenofovir disoproxil fumarate plus emtricitabine reduced the risk of HIV infection by about half – from 37 in 1,000 to 19 in 1,000. Taking tenofovir disoproxil fumarate alone cut the risk by nearly two thirds – from 26 in 1,000 to ten in 1,000. Side-effects were rare, and sexual risk behaviour was similar in each of the groups.

But Dr Okwundu cautions: "It is important to determine how pre-exposure prophylaxis can best be combined with existing programmes, as no strategy is likely to be 100 per cent effective. There are still many questions that need to be answered."

Antiretroviral pre-exposure prophylaxis (PrEP) for preventing HIV in high-risk individuals. Okwundu, C. I. et al. Cochrane Database of Systematic Reviews 2012, Issue 7. Art. No.: CD007189. doi: 10.1002/14651858.CD007189.pub3.