I’m going to post the abstracts from a couple of articles regarding the risk of HIV transmission with the use of condoms. I will give a short review of the study before each abstract.
The first study was conducted in female sex workers (read prostitutes) in Africa. All the participants were supposed to use condoms, some also using nonoxynol-9. Of course not all were compliant. In the group that used condoms WITH nonoxynol-9 the risk was about 15% per 100 women years. If you say that a woman is sexually active with more than one partner from 20-30 years of age, that would amount to a 1.5% risk of HIV transmission. In the women who used condom WITHOUT nonoxynol-9 the risk was about 10% per 100 woman years, which with our fictitious average of women having 10 years of promiscuity (20-30 years old) amounts to about 1% risk of HIV. Of course compliance which was not clearly spelled out in the study is an important issue. Here’s the first study:
Van Damme L, Ramjee G, Alary M et al. Effectiveness of COL-1492, a nonoxynol-9 vaginal gel, on HIV-1 transmission in female sex workers: a randomised controlled trial. Lancet 2002; 360: 971–977.
INTERVENTION Three hundred and seventy-six women were randomized to receive nonoxynol-9 gel (52.5 mg per dose) and 389 women to receive placebo. The women were instructed to use condoms (provided by the study) and gel with every sex act and to reapply the gel if they cleaned their vagina after last intercourse. The women visited the clinic monthly for a physical examination, blood tests, and a fresh supply of gel and condoms. Any curable sexually transmitted disease (STD) detected at screening or during the study was treated.
MAIN OUTCOME MEASURES Incidence of HIV-1 infection and other STDs, side-effects.
MAIN RESULTS About 70% of women stayed in the study for 48 weeks. In almost 500 000 vaginal sex acts, gel was used with condoms 71% of the time, condom alone 18%, and gel alone 9%. There were 59 cases of seroconversion to HIV-1 in the nonoxynol-9 group (14.7 per 100 women-years), compared to 45 cases in the placebo group (10.3 per 100 women-years). The hazard ratio (HR) for HIV-1 infection with nonoxynol-9 use, adjusted for centre, was 1.5 (95% CI 1.0–2.2, *p *= 0.047). The hazard ratios were similar for women who always used condoms and those who sometimes did not. For women who used the gel up to 3.5 times daily, there was no significant difference in risk of HIV-1 infection between the nonoxynol-9 and placebo groups (incidence 8.8 vs 8.1 per 100 women-years, respectively). But for the 32% of women who used the gel > 3.5 times daily, the incidence of HIV-1 infection was 31 per 100 women-years in the nonoxynol-9 group and 15 in the placebo group (HR 1.8, CI 1.0–3.2, *p *= 0.03). Genital lesions with epithelial breach were more likely in women who used the gel > 3.5 times daily, especially in the nonoxynol-9 group, and were associated with a 2-fold increase in the risk of HIV-1 infection. The incidence of Neisseria gonorrhoeae infection was 40 per 100 women-years in the nonoxynol-9 group and 33 in the placebo group (HR 1.2, CI 0.9–1.6, *p *= 0.19) and of Chlamydia trachomatis infection was 26 and 22 per 100 women-years, respectively (HR 1.2, CI 0.8–1.6, p = 0.37).
