Different Results From HIV Prophylaxis Studies
Multiple clinical trials that have been examining the effects of anti-retroviral drugs as a way to prevent HIV infections in healthy heterosexuals have recorded very different results.
Doctors said that the results from three large studies that took place in Africa, which were published in the New England Journal of Medicine, are varied and questions about the groups what would receive the most benefit from these drugs have appeared.
The use of anti-retroviral drugs in HIV-negative patients is called pre-exposure prophylaxis (PrEP). This sort of approach is used in order to prevent healthy patients from contracting the virus during sex with HIV-positive partners.
One of the studies published in the journal included only heterosexual couples. One of the partners was HIV-positive whilst the other was HIV-negative. The study showed that the risk of an HIV infection was reduced with almost 75 percent for the HIV-negative partners that were taking the anti-retroviral drugs. 4,700 couples participated in the study, called Partners PrEP, from 2008 to 2010, in Uganda and Kenya. Patients were randomly given tenofovir, tenofovir & emtricitabine or placebo on a daily basis. The conclusion of the study was that both treatments showed a good response for protecting both men and women. The authors of the study estimate that the patient’s adherence to the drugs was approximately 92 percent.
Another study published in the same journal had to be stopped in April 2011 due to the fact that the group that was being given the anti-retroviral drugs had shown no improvement in the protection level, compared to the group that was receiving placebo pills. This study, known as FEM-PrEP, was a randomized clinical trial that included 2,120 women from Tanzania, Kenya and South Africa. 33 women that were taking the anti-retroviral drugs became infected with HIV. 35 women that were taking placebo got infected as well.
Unlike the other study, authors report an adherence rate of only 40 percent, whilst also having patients reporting side effects such as vomiting and nausea, liver or kidney problems. According to the researchers, the women participated in the study considered themselves at low risk, thus the low overall adherence rate.
The results of the third study which was published, called TDF-2, have shown a 62% efficiency in pre-exposure prophylaxis. The study included 1,219 patients (men and women) from Botswana. All the patients participating in the study were sexually active heterosexuals.
The results shown in previous studies suggested that the risk of an HIV infection was reduced with 44 percent through the use of anti-retroviral drugs in HIV-negative patients. Higher rates were discovered in patients with higher adherence to the treatment scheme.
Professor Myron Cohen and Dr. Lindsey Baden stated in an editorial in the journal that the cause of these different results taken from different studies is still unknown. They also added that more studies concerning PrEP are necessary because of the general approval that in the near future, pre-exposure prophylaxis will be a part of the HIV prevention plan. Authors believe that a management plan is needed for future patient approach.
“The health care provider who recommends pre-exposure prophylaxis needs a management plan that recognizes the effects of the intervention on the patient’s sexual behavior, safety and well-being as well as the ramifications of the intervention for the health of the public”, wrote Cohen and Baden.