Study shows contraceptive diaphragm does not help prevent HIV infection

The recently completed study of the contraceptive female diaphragm indicates that the cervical barrier does not provide any additional benefit over already available HIV prevention strategies in reducing HIV transmission in women. This first randomized controlled trial of the latex diaphragm was funded by the Bill & Melinda Gates Foundation and was conducted by researchers at the University of California, San Francisco. It involved nearly 5000 volunteers in Durban and Johannesburg, South Africa, and Harare, Zimbabwe. Results of the trial showed that HIV incidence rates (see Primer, this issue) among women in the control group who only received condoms and counseling were nearly identical—at around 4%—to those seen in women who also received a diaphragm and lubricating gel. During the 18-month study, 158 new HIV infections occurred in the group of women who received the diaphragm, with 151 occurring in the control group.

Nancy Padian, principal investigator of the trial, says these results do not support adding the diaphragm to the current list of HIV prevention strategies. She promoted the idea of testing the diaphragm, which shields the cervix, as a way to prevent HIV transmission after research showed that the cervix was a potential hot-spot for HIV infection (see VAXNovember 2006 Spotlight article, Capping infection). Prior to starting the efficacy trial, Padian conducted several acceptability studies to determine if African women were willing to use a diaphragm. As with most HIV prevention methods other than vaccines, compliance is a key factor in determining the success of the intervention. In this study, women who received diaphragms reported using them during only 70% of their sexual acts. These women reported that their partners also used condoms 54% of the time, while women in the control group who were not using the diaphragm reported that their partners used condoms 85% of the time.

Since condom use was lower in the diaphragm group, yet the number of new infections was equivalent, it is possible that the diaphragm contributed to protection. However the trial was not designed to compare the protective effects of the diaphragm to condoms. Researchers are still trying to find ways to help protect women who are at an increasingly high risk of HIV infection and may not be able to get their partner(s) to use condoms.