Incident Cases of Sexually Transmitted Infections among Users of Pre-Exposure Prophylaxis for HIV Prevention in...

Emtricitabine/tenofovir disoproxil fumarate [FTC-TDF] is a daily oral medication taken by HIV-negative individuals for pre-exposure prophylaxis (PrEP) to prevent human immunodeficiency virus (HIV) infection. A higher incidence of sexually transmitted infections (STIs) among PrEP users has been reported compared to STI incidence before PrEP use. Asymptomatic incident STI rates were investigated among 78 patients presenting for PrEP in Honolulu, Hawai'i, from April 2018 to May 2019. Testing for oropharyngeal gonorrhea, urethral gonorrhea and chlamydia, rectal gonorrhea and chlamydia, and syphilis was performed. Incident STI percentages were calculated at each follow-up visit. Ninety-seven percent of patients were men who have sex with men (MSM). Forty-seven percent of patients had follow-up data 6 months after initiation and 28% after 1 year. Thirty-two percent of patients self-reported an STI before initiating PrEP. More than half reported anonymous partners. There were 35 positive STI tests during the study period, and 25% of patients had one or more positive tests during this time. At initiation, 17% of patients were found to have an STI, followed by 16% at 3 months, 14% at 6 months, 8% at 9 months, and 5% at 12 months. At all visits, chlamydia was the most common STI detected; at 6 months, 18% of all rectal tests were positive for chlamydia. There were inconsistent condom use and high STI rates from screening during PrEP initiation and follow-up, offering an opportunity to identify asymptomatic STIs in this population. This study is the first report in Hawai'i of STI rates among PrEP users.