Sunday, July 15, 2007
Diaphragm no defense against HIV, study in Africa finds
Diaphragm no defense against HIV, study in Africa finds
Sabin Russell, Chronicle Medical Writer
Friday, July 13, 2007
Advocates for "female-controlled" AIDS prevention were dealt another setback Thursday after a three-year, multimillion-dollar study in Africa found that women who used a latex diaphragm for possible protection against HIV had the same infection rates as those who did not.
As a consequence, researchers concluded that they could not recommend use of a diaphragm as a low-cost intervention that women could use as a means of reducing their risk of HIV infection.
The study was the most closely watched HIV prevention trial for women since January, when researchers abruptly ended studies of a vaginal gel meant to block the virus after early results showed the women who used it had a slightly higher risk of becoming infected.
A similar trial testing whether the contraceptive jelly nonoxynol-9 might work as an anti-HIV microbicide failed in 2000, when the study revealed that prostitutes in South Africa who used it had a significantly higher infection rate than those who were given an inactive placebo gel.
Results of the latest study were published online in advance of Saturday's edition of the British medical journal the Lancet.
"It's very, very disappointing, of course," said Nancy Padian, executive director of the UCSF Women's Global Health Imperative, lead investigator of the diaphragm study. "We were hoping to find a protective effect. ... It's taken me a long time to get over how devastating this is."
Researchers are desperately seeking a low-cost method that women could use -- without the consent of male partners -- to protect themselves against HIV. About 20 percent of adults are infected in Zimbabwe and South Africa, where the experiment was conducted, and women there run twice the risk of infection as men. In cultures where women are traditionally subservient to men, they have less of a say about matters of sex -- when to have it, whom to have it with, and whether condoms or other safer sexual practices will be used.
The study was conducted in Durban and Johannesburg, South Africa, and in Harare, Zimbabwe. It enrolled nearly 5,000 women ages 18-49 and followed them an average of 18 months. Half of the women were given diaphragms and a gel lubricant, while the other half were not. Both groups were also given condoms and extensive counseling to have their partners use them.
By the end of the study, HIV infection rates were high and almost identical: about 4 percent of the women in each arm of the study were infected per year. Infections were found in 158 women given diaphragms and condoms and counseling; 151 women were infected among those given condoms and counseling only.
Padian said one of the more surprising and disappointing results was that the women provided diaphragms reported using them only 70 percent of the time. That finding nevertheless provides valuable information about the importance of monitoring compliance in complex trials such as this one.
Women who were supplied diaphragms reported that their partners used condoms as well only 54 percent of the time, while the women given only condoms reported they were used 85 percent of the time. Because both groups had identical infection rates, that might suggest that diaphragm use is at least as effective as condoms in preventing HIV, but Padian said the trial was not set up to compare the two methods and, therefore, there is no proof of equivalence.
"It bears looking into in the future," she said. "But this doesn't warrant using it as a protective mechanism now."
Since 1994, Padian and her team of researchers had been exploring the possibility that diaphragms might protect against the AIDS virus. The theory held that the cervix -- which can be shielded from semen by a diaphragm -- is the most vulnerable part of the female reproductive tract to HIV infection. The cervix has a thinner protective layer of skin than tissues on the vagina wall and is rich in white blood cells that are the favored target of HIV.
Dr. Nick Hellmann, interim director of HIV and tuberculosis programs for the Bill & Melinda Gates Foundation, said the disappointing results of the diaphragm trial are simply part of the scientific process. "If we knew it would be successful, we wouldn't have to do these trials," he said.
The Gates Foundation, a major funder of AIDS prevention research, sank $37 million into the study.
The foundation also had been a prime funder of the microbicide trial stopped in January. Hellmann said the results will not deter the foundation from continuing to pay for research in the field.
"There have been setbacks, but we know we can do this. It's a matter of finding the right intervention," he said.
Zeda Rosenberg, chief executive of the International Partnership for Microbicides, in Silver Spring, Md., said the diaphragm study -- although it did not use an antiviral gel -- provided valuable information for future studies of such products.
"These studies are incredibly difficult to do, but it is a difficulty that can and must be overcome," she said. "Women are at high risk of infection throughout the world, and they don't have a means of protecting themselves under their control."
Trial and error: past failures, ongoing efforts
Previous trials on female-controlled HIV prevention:
2000 -- Nonoxynol-9, a commonly used contraceptive gel, was thought to have antiviral properties, but large-scale tests in South Africa showed that women who used it had higher HIV infection rates, so it was ruled out as a possible microbicide.
2005-06 -- Family Health International halted a trial in Ghana that attempted to determine whether Savvy, an experimental contraceptive gel, might work against HIV. Researchers determined the study was too small to yield useful results; a second trial in Nigeria was stopped in 2006 after an interim analysis showed it was unlikely to work.
2007 -- Two trials of cellulose sulfate, an experimental microbicide, were stopped in Africa and India after an initial analysis showed it could increase the risk of HIV infection.
2007 -- Researchers concluded they could not recommend use of a diaphragm as a means of reducing a women's risk of HIV infection after a large-scale, three-year trial in South Africa and Zimbabwe showed that participants who used a latex diaphragm had the same rate of HIV infection as those who did not.
2007 -- Results expected at end of year on large-scale trial of Carraguard, a microbicide derived from seaweed.
2008 -- Results expected of a trial studying whether women with herpes simplex 2 infection can reduce their risk of HIV infection by treating their herpes with the antiviral drug acyclovir.
2009 -- Results expected of a trial studying whether men and women taking the AIDS drug Truvada while uninfected can lower their risk of contracting the virus.
2009 -- Results expected for large-scale study of PRO 2000, an experimental microbicide gel that binds to the surface of HIV.
2009 -- Results expected for midsize trial of BufferGel, a microbicide that changes the acid chemistry inside the vagina to produce a hostile environment for the virus.
2010 -- Results expected for midsize trial of experimental microbicide containing a formulation of the AIDS drug tenofovir.
E-mail Sabin Russell at email@example.com.
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