Efficacy of Doxycycline as Preexposure and/or Postexposure Prophylaxis to Prevent Sexually Transmitted Diseases: A Systematic Review and Meta-Analysis.

Introduction: Bacterial sexually transmitted infections (STIs), specifically infection by Chlamydia trachomatis , Neisseria gonorrhoeae , and Treponema pallidum , have an important burden worldwide. The use of doxycycline as preexposure prophylaxis (PREP or doxy-PREP) or postexposure prophylaxis (PEP or doxy-PEP) might be effective as prophylaxis because it is effective against C. trachomatis and T. pallidum .

Aims: Our objective was to evaluate the efficacy of doxycycline as PREP or PEP against bacterial STIs ( C. trachomatis , N. gonorrhoeae , and T. pallidum ).

Methods: A systematic review and meta-analysis of randomized clinical trials of a high-risk group of individuals was conducted to evaluate whether doxycycline is as effective as PREP or PEP in preventing bacterial STIs. The PubMed-MEDLINE (MEDlars online), Cohrane, Scientific Electronic Library Online (SciELO), and Latin America and the Caribbean Literature on Health Sciences ( Literatura Latino-Americana e do Caribe em Ciências da Saúde -LILACS) databases were searched for randomized clinical trials published up to March 2024. Data were extracted from published reports. Hazard ratios (HRs) and risk ratios (RRs) with 95% confidence interval (CI) were pooled across trials.

Main Outcome Measure: The primary end points were any incidence of bacterial STIs and individual STI infections.

Results: A total of 4 studies were included in the analysis, 3 of which evaluated doxy-PEP and 1 evaluated doxy-PREP. In the doxy-PEP group, a total of 1182 participants were evaluated. In the pooled analysis of doxy-PEP studies, the incidence of the first STI was lower in the doxy-PEP group (HR, 0.538 [95% CI, 0.337-0.859]; I2 = 77%; P < 0.05). Regarding individual infections, only 2 studies were included. In the doxy-PEP group, the incidence of individual infection of C. trachomatis was lower compared with controls (RR, 0.291 [95% CI, 0.093-0.911]) ( I2 = 89%; P < 0.05). Because only one study evaluated doxy-PREP, it was not possible to calculate a meta-analysis index; however, the use of doxycycline as PREP was associated with a decrease in the rate of any STI.

Conclusions: The use of doxy-PEP might reduce the first STI, mainly C. trachomatis , if used within 72 hours after condomless sex. The use of doxy-PREP might also decrease the chance of any STI; however, only 1 study was evaluated.