Doxycycline post-exposure prophylaxis is effective and highly acceptable in an urban public sexually transmitted disease clinic: Philadelphia, 2019-2023.

BACKGROUND

We sought to determine real-world effectiveness of doxycycline post-exposure prophylaxis (doxy PEP) in reducing sexually transmitted infections (STI) among men who have sex with men attending an HIV pre-exposure prophylaxis (HIV PrEP) clinic in Philadelphia.

METHODS

Data from eligible HIV PrEP patients who did and did not receive doxy PEP from September 1, 2019-December 31, 2023 were analyzed. We used a cohort study design and Cox models to estimate associations between doxy PEP receipt and incident gonorrhea (GC), chlamydia (CT), and/or syphilis. We also used a crossover design and Poisson models to estimate incidence rate ratios (IRR) for any STI and each STI separately among individuals in the year before and after doxy PEP initiation.

RESULTS

Among the 508 eligible men, most were young men of color and 416 (82%) opted to receive doxy PEP. Receiving doxy PEP was associated with a reduction in any incident STI (hazard ratio [HR] 0.61, 95% confidence interval 0.40-0.93) and any incident CT (HR 0.40, 95% CI 0.21-0.78). Participants experienced a 62% relative reduction in STI rates while taking doxy PEP (IRR 0.38 (95% CI 0.29-0.50), including a reduction in CT (IRR 0.28, 95% CI 0.20-0.39) and GC (IRR 0.49, 95% CI 0.37-0.65).

CONCLUSIONS

We observed a significant reduction in any STI and CT in both analytic arms, suggesting that doxy PEP is effective in real-world settings. Enhancing doxy PEP implementation would likely reduce community STI transmission.