Objectives: To measure the association between spermicide use and HIV infection, adjusting for condom use, and to measure the association between condom use and HIV infection, adjusting for spermicide use.
Design: Prospective study of women using nonoxynol-9 (N-9) spermicides and latex condoms, with up to 12 monthly clinic visits for interviews, examinations and tests, and re-supply.
Methods: A total of 273 HIV-negative women with multiple sexual partners were enrolled, given latex condoms and N-9 vaginal spermicidal suppositories, and advised to use both every time they had sexual intercourse. Participants recorded data on sexual activity on pictorial coital logs. New HIV infections were detected and confirmed by quarterly enzyme-linked immunosorbent assays and Western blots, respectively.
Results: Nineteen HIV infections occurred during mean follow-up of 8.1 months (an incidence rate of 10.4 infections per 100 women-years). The adjusted HIV rate ratio (RR) was 0.1 [95% confidence interval (CI), 0.1-0.6] for more consistent compared with less consistent spermicide users; and 1.1 (95% CI, 0.4-2.9) for more consistent compared with less consistent condom users. Among the subgroup of experienced condom users, the RR for more versus less consistent condom use was 0.3.
Conclusions: This is the first epidemiological evidence that N-9 spermicides can reduce the incidence of HIV infection. A more definitive randomized clinical trial is urgently needed.
PIP: In a prospective study, the association between spermicide use and HIV infection was measured, adjusting for condom use, the association between condom use and HIV infection, and spermicide use. A total of 273 HIV-negative female prostitutes, the majority of them in their twenties, were enrolled in the study in Yaounde, Cameroon in 1989-1990. They made up to 12 monthly clinic visits for interviews, examinations, tests, and re-supply of condoms and spermicide. When they were admitted to the study, they were given plain lubricated latex condoms and N-9 vaginal spermicidal suppositories containing 100 mg N-9, and they were advised to use both every time they had sexual intercourse. Participants recorded data on sexual activity and barrier method use on pictorial coital logs (calendars on which coitus, condom use, and spermicide use could be marked). New HIV infections were detected and confirmed by quarterly enzyme-linked immunosorbent assays and Western blots, respectively. Both consistent spermicide use and consistent condom use were associated with lower incidences of gonorrhoea and genital ulcers. 19 HIV-seroconversions (7.0% of the 273 women) occurred during a mean follow-up of 8.1 months (an incidence rate of 10.4 infections per 100 woman-years). The HIV rate ratio (RR) for more consistent spermicide users ( or = 67% use) compared with less consistent users was 0.2 (95% CI, 0.1-0.7), indicating substantial protection against HIV. The HIV RR for more consistent condom users ( or = 63% use) compared with less consistent users was 0.8 (95% CI, 0.3- 2.0), suggesting slight protection. Adjusting for condom use, the RR for more versus less consistent spermicide use was 0.1 (95% CI, 0.1- 0.6). Adjusting for spermicide use, the RR for more versus less consistent condom use was 1.1 (95% CI, 0.4-2.9). Among the subgroup of experienced condom users, the RR for more versus less consistent condom use was 0.3. These findings prove that N-9 spermicides can reduce the incidence of HIV infection.