June 14, 2019
2 min read

PrEP use and increasing incidence of STIs: Addressing the syndemic

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Monica Gandhi

In a recent study published in JAMA, researchers found that among a cohort of predominantly gay and bisexual men, the initiation of HIV pre-exposure prophylaxis, or PrEP, was linked with an increased incidence of STIs (adjusted incidence rate ratio = 1.12; 95% CI, 1.02-1.23). The study did not include a control group that did not receive PrEP, so researchers were unable to determine if PrEP initiation was the cause of the increase in STI risk. However, given the high degree of protection PrEP offers, some experts are concerned that patients may change their sexual risk behaviors and exacerbate the STI epidemic.

Monica Gandhi, MD, MPH, professor of medicine at the University of California, San Francisco, and medical director of the “Ward 86” HIV Clinic at Zuckerberg San Francisco General Hospital, and colleagues wrote an accompanying editorial to the JAMA study. Infectious Diseases in Children asked Gandhi whether PrEP use leads to risk compensation and how physicians should address this problem.

The Australian PrEPX study showed that there is an increased rate of bacterial STIs among men who have sex with men (MSM) in the PrEP era. This is likely not just a result of testing more for STIs when MSM are on PrEP but also due to changes in behavior and less condom use in the face of highly effective prevention strategies such as PrEP.

In my opinion as an HIV clinician, the director of a large HIV clinic and a prescriber of PrEP for at-risk MSM, this study does not shed negative light on PrEP at all but highlights an opportunity we have as sexual health providers to turn the tide of the STI epidemic as we tackle HIV prevention. STIs and HIV have always been and will always be intertwined. Because PrEP prescribing requires regular STI screening among MSM, this study highlights the importance of prompt STI screening and treatment for those with STIs and prompt partner notification and treatment to prevent further spread when PrEP is being used. We have always had the tools to prevent and treat STIs; we now can put these tools to use as we see and screen MSM more often in the context of PrEP.

Importantly, offering PrEP to patients and preventing STIs should not be viewed as a trade-off. Both epidemics are intertwined, and both epidemics are now addressable. We need to expand treatment as prevention to reach all those living with HIV worldwide, and we need to massively expand PrEP use in the United States and worldwide to prevent further infections. Increased PrEP prescribing will lead to more frequent STI screening, which will eventually lead to a reduction in overall STI prevalence and incidence. We are at a turning point in the HIV and STI syndemic, and this is an exciting time to bend the curve on both epidemics worldwide.

Disclosure: Gandhi reports no relevant financial disclosures.

Editor's note: To read our June cover story, click here.