Treating to Prevent HIV
posted: 03/03/2011
Could people who do not have HIV use HIV treatment drugs (PrEP) to stop themselves from getting HIV? The detailed results just out for gay and bi men are better than the early findings. This means PrEP could be approved for use in the USA by the end of the 2011.
Last year, the first results from a study of gay and bisexual men appeared. Taking PrEP cuts gay and bi men’s risk of getting HIV. But there were worries because many of the men did not take all the tablets. Some men got HIV.
HIV infection
Much better updated results were announced at the CROI conference in Boston, USA, that has just ended.
In the different places where the trial took place, including South Africa, the taking of PrEP (HIV drugs to prevent HIV infection) varied a lot.
Gay and bi men in the two USA cities (Boston and San Francisco) of the international iPrEx study of tenofovir/FTC (Truvada) had near-perfect HIV-prevention drug taking, compared with 50% tablet taking at the other sites.
And the men taking the greatest sexual risks for HIV, by having unprotected receptive anal sex, were taking the prevention treatment better than men taking less HIV risks – which is good to know.
USA approval within a year?
Lead investigator Bob Grant announced that the US Food and Drug Administration (FDA) had agreed that the trial results were good enough for the FDA to consider allowing the use of Truvada to prevent HIV. PrEP, as a result, might be approved in the USA by the end of this year.
First USA Guidelines for gay men published
Interim Guidance: Pre-exposure Prophylaxis for the Prevention of HIV Infection in Men Who Have Sex with Men from USA Centers for Disease Control and Prevention.
2500 men and the results
There were almost 2500 men in this trial and 130 of them got HIV by the end. Like most drug trials men were randomly split into two groups and told they would either get Truvada, or a dummy pill, but no-one would know who was taking what, until the end. The men were therefore warned they should still use condoms, because half were using the dummy pill.
48 of the men who got HIV took the Truvada and 82 of the men who were taking the dummy pills, a HIV infection rate of 2.6% a year. Another 10 other men have HIV, but they already had the symptoms of HIV infection when they joined the study.
This means that the final ‘how well does it work’ rate in the ‘modified intent to treat’ analysis, (this leaves out the 10 men who started the study with HIV, and ignores things like different rates of tablet-taking and the men’s level of sexual risk-taking), was 42%.
PrEP worked better when men were over 25 (56%), among men who took more than 9 out of 10 of the tablets (68%), and among the men who were circumcised (76%).
Would PrEP be cost effective?
Other new studies have now looked at the value for money of treating people to prevent HIV in South Africa. The answer is mixed.
It is usually cheaper to treat the person with HIV than treating one or more HIV negative people with PrEP. Treating the person with HIV should reduce their viral load so it becomes undetectable and their chance of passing on HIV then becomes very small. In mixed status couples, that may be enough protection for many. But PrEP would help protect negative partners who have unsafe sex outside the main relationship and who don't use condoms.
Source and more details
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