Does postexposure prophylaxis with doxycycline in men who have sex with men or transgender women who are either living with human immunodeficiency virus or using preexposure prophylaxis reduce the risk of sexually transmitted infection?
Men who have sex with men and transgender women who have or are at risk of HIV disease benefit from taking a single dose of doxycycline 200 mg following condomless sexual intercourse (NNT = 5). The patients studied were at high risk of STI based on a history of condomless anal or oral sex with a man and a diagnosis of gonorrhea, chlamydia, or early syphilis in the past 12 months.
Randomized controlled trial (nonblinded)
These researchers enrolled 501 men who have sex with men and transgender women who were either using preexposure prophylaxis (PrEP; n = 327) or who were living with human immunodeficiency virus (HIV; n = 174). All but 19 participants in this intention-to-treat population were men who have sex with men. The median age of the participants was 38 years, 7% were Black, 11% were Asian or Pacific Islander, and 15% were multiracial. This was a particularly high-risk group: All participants had been given a diagnosis of gonorrhea (68%), chlamydia (58%), or syphilis (20%) in the past year, and 43% had 2 or more sexually transmitted infections (STIs). The patients were randomized (in a 2:1 ratio) to receive doxycycline 200 mg taken ideally within 24 hours and no more than 72 hours after a condomless sexual encounter. Groups were balanced at baseline and analysis was by intention to treat. Participants were tested quarterly for the 3 STIs studied, and also asked about any diagnoses at other clinical encounters in the past 3 months. After a median 9-month follow-up, the intervention group had a significantly lower likelihood of any STI at a quarterly visit. This was true both for the PrEP group (10.7% vs 31.9%; P < .001; number needed to treat [NNT] = 5) and the group living with HIV (11.8% vs 30.5%; P < .001; NNT = 5). The reduction was consistent across all 3 STIs studied. There was some indication of increased resistance to doxycycline in the treatment group in both gonorrhea and Staphylococcus aureus cultures. This will require further study, especially the implications for resistance in other infections. There were no serious adverse events; 89% of participants reported that taking doxycycline was acceptable or very acceptable, and 86% reported “always or often” taking doxycycline for postexposure prophylaxis as directed.
Mark H. Ebell, MD, MS
University of Georgia