Association of HIV Preexposure Prophylaxis With Incidence of Sexually Transmitted Infections Among Individuals at High Risk of HIV Infection

Abstract

Emerging evidence suggests that risk of bacterial sexually transmitted infections (STIs) increases among gay and bisexual men following initiation of HIV preexposure prophylaxis (PrEP). OBJECTIVE To describe STI incidence and behavioral risk factors among a cohort of predominantly gay and bisexual men who use PrEP, and to explore changes in STI incidence following PrEP commencement. DESIGN, SETTING, AND PARTICIPANTS The Pre-exposure Prophylaxis Expanded (PrEPX) Study, a multisite, open-label intervention study, was nested within the Australian Collaboration for Coordinated Enhanced Sentinel Surveillance (ACCESS) clinic network. A total of 4275 participants were enrolled (July 26, 2016-April 1, 2018) in Victoria, Australia. Of these, 2981 enrolled at 5 ACCESS clinics (3 primary care, 1 sexual health, and 1 community-based HIV rapid testing service), had at least 1 follow-up visit, and were monitored until April 30, 2018. EXPOSURES Upon enrollment, participants received daily oral tenofovir disoproxil fumurate and emtricitabine for HIV PrEP, quarterly HIV and STI testing, and clinical monitoring. MAIN OUTCOMES AND MEASURES The primary outcome was incidence of chlamydia, gonorrhea, or syphilis. Incidence rates and hazard ratios describing behavioral risk factors of STI diagnosis were calculated. Incidence rate ratios (IRRs), adjusted for change in testing frequency, described changes in STI incidence from 1-year preenrollment to study follow-up among participants with preenrollment testing data (n = 1378). RESULTS Among the 2981 individuals (median age, 34 years [interquartile range, 28-42]), 98.5% identified as gay or bisexual males, 29% used PrEP prior to enrollment, 89 (3%) withdrew and were censored at date of withdrawal, leaving 2892 (97.0%) enrolled at final follow-up. During a mean follow-up of 1.1 years (3185.0 person-years), 2928 STIs were diagnosed among 1427 (48%) participants (1434 chlamydia, 1242 gonorrhea, 252 syphilis). STI incidence was 91.9 per 100 person-years, with 736 participants (25%) accounting for 2237 (76%) of all STIs. Among 2058 participants with complete data for multivariable analysis, younger age, greater partner number, and group sex were associated with greater STI risk, but condom use was not. Among 1378 participants with preenrollment testing data, STI incidence increased from 69.5 per 100 person-years prior to enrollment to 98.4 per 100 person-years during follow-up (IRR, 1.41 [95% CI, 1.29-1.56]). After adjusting for testing frequency, the increase in incidence from 1 year preenrollment to follow-up was significant for any STI (adjusted IRR, 1.12 [95% CI, 1.02-1.23]) and for chlamydia (adjusted IRR, 1.17 [95% CI, 1.04-1.33]). CONCLUSIONS AND RELEVANCE Among gay and bisexual men using PrEP, STIs were highly concentrated among a subset, and receipt of PrEP after study enrollment was associated with an increased incidence of STIs compared with preenrollment. These findings highlight the importance of frequent STI testing among gay and bisexual men using PrEP.

In response to Saunders et al RE: STI testing and rates in MSM using PrEP

“…We agree, as the respondents point out, that men who have sex with men (MSM) using pre-exposure prophylaxis (PrEP) are a bias group in that they are more likely to have confounding factors contributing to increased rates of sexually transmitted infections (STIs), compared with MSM not using PrEP. Interestingly, recent longitudinal data have suggested that STI rates, particularly rates of rectal STIs, may increase in MSM who start using PrEP [2]. Our data draw attention to local real-life STI rates in a defined population of MSM, and show that MSM using PrEP were more likely to test positive for an STI when they presented to services, which is important when access to testing is decreasing [3,4].…”

“…Public Health England (PHE) produced mathematical modelling to suggest that their original numbers in IMPACT were an accurate reflection of demand, but have recently doubled the numbers [5]. Anecdotally, we see many MSM who are unable to access PrEP, highlighting that MSM using PrEP make up diverse populations where HIV infection risk may differ as described in the Australian longitudinal study [2].…”

Current challenges in the clinical management of sexually transmitted infections

“…Preliminary indications of risk compensation in PrEP demonstration projects and observational studies are conflicting . This discrepancy might arise from decreased onward transmission of STIs due to more frequent STI screening, whereas ascertainment bias may increase STI detection.…”

Impact of the OPTN transmissible diseases policy and US PHS increased risk donor guidelines on living donor candidates

“…35,36 Behavioral interventions have been shown to be an efficacious method of HIV / sexually transmitted infection (STI) disease prevention in other settings, and they may have positive effects on risk reduction. [37][38][39][40] These approaches are not fail safe, and have not yet been tested in the living donor setting.…”