Factors associated with reporting antibiotic use as STI prophylaxis among HIV PrEP users: findings from a cross-sectional online community survey, May-July 2019, UK.

OBJECTIVES: The use of antibiotics as pre-exposure or postexposure prophylaxis for sexually transmitted infection (STI) prevention (STI prophylaxis) is not currently recommended in the UK, but there is evidence that self-prescribing occurs among those at greatest risk. We present the prevalence and factors associated with STI prophylaxis among a community sample of HIV pre-exposure prophylaxis (PrEP) users. METHODS: The 2019 online PrEP User Survey ran between 17 May and 1 July. Eligible participants included UK residents reporting HIV PrEP use or having tried to obtain HIV PrEP since January 2017. STI prophylaxis use was defined as reporting buying antibiotics to prevent STIs, either privately or through the internet; this question was only asked to HIV PrEP users. Factors associated with STI prophylaxis use were assessed using univariable and multivariable logistic regression. RESULTS: Overall, 9% (167/1856) of HIV PrEP users reported STI prophylaxis use; 97% were gay or bisexual men, 84% reported white ethnicity, 55% resided in London and 69% were aged ≥35 years. Factors associated with STI prophylaxis included: reporting ≥5 compared with 1-4 condomless sex partners in the past 6 months (12% vs 5.6%, adjusted odds ratio (aOR)=1.80; 95% CI 1.22 to 2.64), reporting chemsex drug use compared with no sexualised drug use in the past 12 months (13% vs 6.0%, aOR=1.88; 95% CI 1.20 to 2.93) and reporting an STI diagnosis in the past 12 months (12% vs 6.6%, aOR=1.54; 95% CI 1.08 to 2.18). Variables not significant in multivariable analyses included: ethnicity, age, residence and HIV PrEP sourcing. CONCLUSIONS: Approximately 1 in 10 HIV PrEP users from this community sample reported self-prescribed STI prophylaxis. STI prophylaxis was associated with sexual behaviour known to facilitate STI transmission and with a history of recent STIs acquisition. Given the potential risk of antimicrobial resistance, sexual health clinicians should consider asking attendees, especially HIV PrEP users, about the use of antibiotics as STI prophylaxis, to inform appropriate counselling, testing and management.

Economic evaluation of HIV pre-exposure prophylaxis among men-who-have-sex-with-men in England in 2016.

Clinical effectiveness of pre-exposure prophylaxis (PrEP) for preventing HIV acquisition in men who have sex with men (MSM) at high HIV risk is established. A static decision analytical model was constructed to inform policy prioritisation in England around cost-effectiveness and budgetary impact of a PrEP programme covering 5,000 MSM during an initial high-risk period. National genitourinary medicine clinic surveillance data informed key HIV risk assumptions. Pragmatic large-scale implementation scenarios were explored. At 86% effectiveness, PrEP given to 5,000 MSM at 3.3 per 100 person-years annual HIV incidence, assuming risk compensation (20% HIV incidence increase), averted 118 HIV infections over remaining lifetimes and was cost saving. Lower effectiveness (64%) gave an incremental cost-effectiveness ratio of + GBP 23,500 (EUR 32,000) per quality-adjusted life year (QALY) gained. Investment of GBP 26.9 million (EUR 36.6 million) in year-1 breaks even anywhere from year-23 (86% effectiveness) to year-33 (64% effectiveness). PrEP cost-effectiveness was highly sensitive to year-1 HIV incidence, PrEP adherence/effectiveness, and antiretroviral drug costs. There is much uncertainty around HIV incidence in those given PrEP and adherence/effectiveness, especially under programme scale-up. Substantially reduced PrEP drug costs are needed to give the necessary assurance of cost-effectiveness, and for an affordable public health programme of sufficient size.