AEGiS-14IAC: A randomized, placebo-controlled trial of monthly azithromycin to prevent sexually transmitted infections (STI) and HIV in Kenyan female sex workers (FSWs).

14th International AIDS Conference

Barcelona, Spain - July 7-12, 2002

A randomized, placebo-controlled trial of monthly azithromycin to prevent sexually transmitted infections (STI) and HIV in Kenyan female sex workers (FSWs).

Int Conf AIDS 2002 Jul 7-12; 14:(abstract no. TuOrD1151)

Kimani J, Kaul R, Ngugi EN, Bwayo JJ, Fonck K, MacDonald KS, Temmerman M, Moses S
Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya

BACKGROUND: STI are common in FSWs, increase HIV susceptibility and are often asymptomatic. Antibiotic prophylaxis may reduce risk for STI acquisition, thus reducing risk of HIV infection. We designed a clinical trial to assess if antibiotic prophylaxis reduces HIV acquisition in FSWs.

METHODS: In May 1998 we established a cohort of HIV seronegative FSWs in Nairobi, half of whom are randomly assigned to receive 1 gm of azithromycin monthly and the other half a placebo, in a double-blind fashion. All women are counseled to reduce risk for STI, and risk behaviour is assessed at baseline and 3-monthly follow-up visits. Urine is collected monthly for STI determinations, and full physical examinations, including STI work-ups, are performed at baseline and at 6-monthly intervals.

RESULTS: By November 2001, 457 women had been enroled. At enrolment, they reported a mean of 15.2 sex partners per week, 22% reported never using condoms in the past month and 17% always using condoms. At their most recent follow-up visit, they reported a mean of 4.1 sex partners per week and 61% reported always using condoms. Reductions in partners and increases in condom use were statistically significant and associated with reduced STI incidence (P < 0.001). 28 women sero-converted to HIV-1 in approximately 718 person-years (PYs) of follow-up, for an annualized HIV incidence of 3.9 per 100 PYs. Incidence of gonorrhea was 4.7% by cervical culture/PCR and 10.2% on urine PCR; chlamydial infection 3.8% by cervical PCR and 14.9% on urine PCR; and syphilis incidence 1.7%. Genital ulcers (GUs) were observed on only 6 follow-up visits.

CONCLUSION: HIV incidence in this cohort of high-risk women is much lower than anticipated, likely due to a combination of behavioural change after enrolment and the low STI incidence, particularly GUs. We have increased the planned sample size to reach the study endpoints. Other HIV prevention studies such as vaccine trials will face similar challenges, as successful promotion of condom use and other safer sex practices in high-risk individuals can greatly reduce risk for HIV acquisition.

Keywords: AEGIS, HIV Infections, Condoms, Azithromycin, HIV Seropositivity, Incidence, Placebos, Safe Sex, Sexual Partners, HIV-1, Risk-Taking, Randomized Controlled Trials, Gonorrhea, Acquired Immunodeficiency Syndrome, Syphilis, Condoms, Female, Human, Female

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TuOrD1151