Effects Of HIV Oral Pre-Exposure Prophylaxis On Incidence Of STIS Among Female Sex Workers In Selected Drop-In Centers In Nairobi County

Abstract

Pre-exposure Prophylaxis (PrEP) is effective in prevention of Human Immunodeficiency Virus (HIV) infections among populations at a substantial risk. World Health Organization recommends use of PrEP for prevention of HIV, however, risk of sexually transmitted Infections (STIs) raises concern. While STIs screening is continually done at PrEP refill visits and cases treated, increased risk of STIs may reduce the prevention benefits of PrEP while increasing STI rates with ultimate impact on economic and health burdens. This study investigated the effects of HIV oral PrEP on the incidences of STIs and risky sexual behaviours among female sex workers in Nairobi. Specifically, the study; compared the incidence rate of bacterial STIs and identified the STIs between FSWs taking HIV oral PrEP and non-PrEP user FSWs in Nairobi. A six months retrospective cohort study was conducted among FSWs comprising of both HIV oral PrEP users and non-PrEP users accessing services at selected Drop-in Centres (DICEs) in Nairobi County. Multi stage sampling was employed to select Sub Counties, DICEs and participants, to generate a sample size of 168 PrEP users and 168 non-PrEP users. A structured data abstraction tool was used to collect data on STI incidences. Data was analysed using STATA. Oral PrEP users were found to be 1.7 times higher risk of acquiring STIs (P=0.064, 95%CI) than non-PrEP users. Vaginitis (52.1%) and cervicitis (21.8%) were the most common STIs identified among FSWs. Composite STI prevalence of 35.4 and pooled STI incidence rate of 70.8 per 100-person years was observed. This study demonstrated an increasing trend of STIs among FSWs using HIV PrEP; 0%, 7%, 13%, 16%, and 21%, from enrolment to month five, with the most notable STIs being vaginitis, cervicitis and Pelvic Inflammatory Disease (PID). Oral PrEP use does not increase STI risk, however there was a notable increasing trend of STI cases through the six-month study period. STIs prevention counselling should therefore be emphasized during PrEP initiation and throughout PrEP follow up visits.