Efficacy of postexposure prophylaxis with doxycycline (Doxy-PEP) in reducing sexually transmitted infections: a systematic review and meta-analysis.

Objectives: This systematic review aimed to identify the efficacy, adherence, safety and impact on antimicrobial resistance of postexposure prophylaxis with doxycycline (Doxy-PEP) in different populations.

Methods: We searched MEDLINE (via PubMed), Embase and Cochrane CENTRAL databases from inception to 29 May 2024. Two reviewers independently screened the studies and extracted data. We included randomised clinical trials that evaluated the efficacy of Doxy-PEP within 72 hours after condomless sex. A random-effects meta-analysis was conducted to compare the risk of bacterial sexually transmitted infections (STIs) between Doxy-PEP and no prophylaxis. The risk of bias was assessed with the risk-of-bias tool for randomized trials (RoB 2) and the certainty of evidence (CoE) with Grading of Recommendations Assessment, Development and Evaluation (GRADE).

Results: Four studies were included in the systematic review, totalling 1727 participants. Studies were conducted between 2015 and 2022. Most participants (73%) were men who have sex with men, and the median age of participants varied from 24 to 43 years. Doxy-PEP reduced the risk of having any bacterial STI in different populations by 46% (hazard ratio (HR) 0.54; 95% CI 0.39 to 0.75; CoE moderate), the risk of chlamydia by 65% (relative risk (RR) 0.35; 95% CI 0.15 to 0.82; CoE low) and syphilis by 77% (RR 0.23; 95% CI 0.13 to 0.41; CoE high), without significant effect for risk of gonorrhoea infection (RR 0.90; 95% CI 0.64 to 1.26; CoE very low). The self-reported adherence rate of Doxy-PEP was approximately 80% and one drug-related serious adverse event was reported.

Conclusion: Doxy-PEP reduced the incidence of chlamydia and syphilis infections. No significant reduction in gonorrhoea infection was observed. This strategy seems promising for some high-risk groups; however, there is still a lack of information on the induction of bacterial resistance and long-term adverse events. PROSPERO REGISTRATION NUMBER.