PrEP and Risk for Sexually Transmitted Infections: Implications for Practice

Paul E. Sax, MD


May 03, 2019

This transcript has been edited for clarity.

Hi. This is Dr Paul Sax from Brigham and Women's Hospital and Harvard Medical School. Today I want to review a study that was recently published in JAMA[1] on the incidence of sexually transmitted infections (STIs) among individuals taking preexposure prophylaxis (PrEP) for HIV.

The data thus far on whether PrEP increases the risk for STIs have been mixed, but a lot of these data have come from randomized clinical trials, and there are reasons why those data may not be accurate for clinical practice. First, the people who participated in those studies are not necessarily the same as people receiving PrEP through clinical practice. Second, some of the studies had a placebo arm, so individuals didn't know whether they were receiving active protection or not.

To answer the question about whether PrEP increases risk for STIs, investigators in Australia looked at a large number of mostly gay and bisexual men who received PrEP as part of a very large rollout in that country. They measured STI incidence over time and had a few very interesting findings. First, PrEP was associated with an increased risk for STIs in this population, even after adjusting for the increased frequency of testing that occurs once a person starts PrEP. The second thing they found that I thought was very interesting and important for us is that a relatively small proportion of participants (25%) accounted for three fourths of the STIs that occurred during follow-up.

These data show us that there are differences in risk among those who receive PrEP. The study also raises several important questions. One is whether there should be some form of postexposure prophylaxis, such as the doxycycline strategy that was tested in one study,[2] for individuals at very high risk or people who have had repeated infections. A second question is how do we incorporate these data into our monitoring strategies? It may be that some individuals require very frequent STI checks and others need less frequent monitoring. A third question that I think is very important, and hasn't been figured out yet, is how do we operationalize the prescribing and monitoring of PrEP? There's been a sense that it's been overmedicalized, which has restricted access to PrEP among those who need it most. We have to remember also that these are the people who are at highest risk for STIs and of acquiring HIV, so they need to be monitored.

Finally, I want to emphasize that these data do not in any way say that prescribing PrEP is a bad idea for people at risk for HIV infection. Australia has seen a dramatic drop in HIV incidence in their country since the widespread rollout of PrEP among those at risk.

This is Paul Sax, and I've been covering a paper on PrEP and STIs that was recently published in JAMA. Thanks so much.

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