Antiretroviral therapy coverage associated with reduced HIV incidence in Kenya

Impact of community antiretroviral therapy coverage on HIV incidence in Kenyan female sex workers: a 15-year prospective cohort study.

McClelland RS, Richardson BA, Cherutich P, Mandaliya K, John-Stewart G, Miregwa B, Odem-Davis K, Jaoko W, Kimanga D, Overbaugh J. AIDS. 2015 Jul 31. [Epub ahead of print]

Objective: To test the hypothesis that increasing community antiretroviral therapy (ART) coverage would be associated with lower HIV incidence in female sex workers (FSWs) in Mombasa District, Kenya.

Design: Prospective cohort study.

Methods: From 1998 to 2012, HIV-negative FSWs were asked to return monthly for an interview regarding risk behavior and testing for sexually transmitted infections including HIV. We evaluated the association between community ART coverage and FSW's risk of becoming HIV infected using Cox proportional hazards models adjusted for potential confounding factors.

Results: One thousand four hundred four FSWs contributed 4335 woman-years of follow-up, with 145 acquiring HIV infection (incidence 3.35/100 woman-years). The ART rollout began in 2003. By 2012, an estimated 52% of HIV-positive individuals were receiving treatment. Community ART coverage was inversely associated with HIV incidence (adjusted hazard ratio 0.77; 95% confidence interval 0.61-0.98; P = 0.03), suggesting that each 10% increase in coverage was associated with a 23% reduction in FSWs' risk of HIV acquisition. Community ART coverage had no impact on herpes simplex virus type-2 incidence (adjusted hazard ratio 0.97; 95% confidence interval 0.79-1.20; P = 0.8).

Conclusion: Increasing general population ART coverage was associated with lower HIV incidence in FSWs. The association with HIV incidence, but not herpes simplex virus type-2 incidence, suggests that the effect of community ART coverage may be specific to HIV. Interventions such as preexposure prophylaxis and antiretroviral-containing microbicides have produced disappointing results in HIV prevention trials with FSWs. These results suggest that FSWs' risk of acquiring HIV infection might be reduced through the indirect approach of increasing ART coverage in the community.

Abstract access [1]

Editor’s notes: The individual-level benefit of antiretroviral therapy (ART) on reducing HIV transmission between serodiscordant partners is established, but less is known about a possible population-level effect of ART on key populations such as female sex workers. In this study of 1404 initially HIV-negative female sex workers in Mombasa, Kenya, increased community ART coverage was strongly associated with reduced HIV incidence. HIV incidence was 23% lower for every 10% increase in ART coverage, after adjusting for HIV prevalence and participants’ behavioural characteristics. However, the authors note that HIV incidence was already declining prior to the introduction of ART (from 11.4 cases/100 woman-years in 1998 to 7.6/100 woman-years in 2002), due to other factors including changes in risk behaviour and HIV-prevention efforts in the community. Despite this, the present study suggests that in the setting of ongoing high-quality HIV prevention services, the risk of HIV acquisition among female sex workers is likely to be reduced by increasing ART coverage in the community. Moves to increase coverage of ART in the community will potentially have a substantial HIV prevention benefit on this key population.

Africa [9]
Kenya [10]
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