20th International AIDS Conference - Melbourne, Australia


THPE127 - Poster Exhibition

Potential cost-effectiveness of a pre-exposure prophylaxis intervention for female sex workers in Nairobi: prioritizing within a core group

I. Cremin1, L. McKinnon2, J. Kimani3, N. Kilonzo4, P. Cherutich5, G. Gakii6, F. Muriuki6, K. Kripke7, S. Resch8, R. Hecht9, L. Gelmon3, T. Hallett10

1Imperial College London, Department of Infectious Disease Epidemiology, London, United Kingdom, 2CAPRISA, Durban, South Africa, 3University of Manitoba and University of Nairobi, Nairobi, Kenya, 4LVCT, Nairobi, Kenya, 5National AIDS and STI Control Programme, Nairobi, Kenya, 6Sex Worker Outreach Program, Nairobi, Kenya, 7Futures Institute, Washington DC, United States, 8Harvard School of Public Health, Boston, United States, 9Results for Development Institute, Washington DC, United States, 10Imperial College London, London, United Kingdom

Background: PrEP is being considered as component of combination prevention for key populations in Kenya. We investigated the potential epidemiological impact and cost-effectiveness of a PrEP intervention prioritized within the Female Sex Worker (FSW) population in Nairobi.
Methods: A mathematical model was developed to represent sexual transmission of HIV, in Nairobi. The representation of sex work in the model was guided by analyses of behavioural data from the Sex Worker Outreach Program (SWOP) in Nairobi. The model was calibrated to incidence and prevalence data among key populations and the wider population of Nairobi. Implementation of existing interventions (reduced risk behaviour, male circumcision and antiretroviral therapy) was represented. PrEP was assumed to provide a 90% reduction in risk of acquisition per PrEP-protected sex act. Optimistically, the majority (80%) of PrEP users were assumed to be ''good adherers''. A PrEP unit cost of $408 was assumed, based on a comprehensive costing exercise conducted at the SWOP clinic.
Results: A PrEP intervention prioritized for FSWs at highest risk of acquisition (an identifiable sub-group with incidence > 9 per 100 PY) would result in 19% of infections among FSW averted, at $3,150 per infection averted (from a PrEP program perspective over a ten year intervention period (2015-2025)). Alternatively, providing PrEP to FSWs regardless of their risk of acquisition and assuming an annual budget reaching $10 million (corresponding to a peak of 67% of all uninfected FSWs receiving PrEP in 2020), would avert 34% of infections among FSW. The cost per infection averted is high, at approximately $16,600 per infection averted, and varies little with respect to the level of annual spending on PrEP, but is highly sensitive to the level of adherence, increasing dramatically (>$22,800) as adherence is reduced (< 50% of PrEP users assumed to be ''good adherers'').
Conclusions: The impact and cost-effectiveness of a PrEP intervention for FSWs in this setting are largely determined by; the ability to prioritize to those with highest risk of acquisition and the level of adherence among those who receive PrEP, and need to be considered in the context of the impact and cost-effectiveness of existing interventions.

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