A Pilot, Randomized Controlled Trial of Dual Daily HIV and Sexually Transmitted Infection Pre-exposure Prophylaxis Using Tenofovir Disoproxil Fumarate/Emtricitabine and Doxycycline in Gay, Bisexual, and Other Men Who Have Sex With Men and Transgender Women: The DuDHS Study.

BACKGROUND

Men who have sex with men (MSM) and transgender women experience high sexually transmitted infection (STI) rates. This study evaluated the feasibility of doxycycline pre-exposure prophylaxis (doxyPrEP) for STI prevention in these key populations.

METHODS

Sexually-active MSM and transgender women without human immunodeficiency virus (HIV) with prior syphilis were recruited. Participants initiated HIV PrEP with tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) daily for 48 weeks and were randomized 1:1 to daily doxyPrEP for 48 weeks (immediate arm), or doxyPrEP initiated at 24 weeks (deferred arm). Primary outcomes included adherence, measured using questionnaires, along with tolerability; STI incidence (chlamydia, gonorrhea, syphilis) was a secondary outcome. Nasal carriage of Staphylococccus aureus was assessed serially for doxycycline resistance.

RESULTS

Fifty-two participants were enrolled into the immediate (n = 26) and deferred (n = 26) arms. At 48 weeks, self-reported adherence (≥95%) was 75.0% versus 66.7% (P = .538) for TDF/FTC, and 70.8% versus 61.9% (P = .526) for doxycycline in the immediate versus deferred arms, respectively. No doxyPrEP-related serious adverse events occurred. Incidence of any STI at 24 weeks was reduced in the immediate versus deferred arms, and over 48 weeks, being on doxycycline (vs being off; ie, first 24 weeks of deferred arm) was associated with STI reduction (adjusted odds ratio [aOR] 0.36; 95% confidence interval [CI]: .15-.89). Emergent doxycycline-resistant S. aureus was identified in six individuals, with five in the immediate arm (P = .077).

CONCLUSIONS

Dual HIV/doxyPrEP is feasible and associated with a significant reduction in incident STI. Further evaluation of dosing strategies, efficacy and impact on antimicrobial resistance is warranted.