A cross-sectional analysis of doxyPEP use and outcomes in Michigan, United States

<b>Background:</b> In 2024, national guidance was issued for doxycycline post-exposure prophylaxis (doxy-PEP) to prevent bacterial sexually transmitted infections (STIs). The study purpose was to evaluate doxy-PEP use in patients with increased risk of STI exposure at a large, urban health system. <b>Methods:</b> IRB-exempt study of adult patients with clinic encounters for increased risk of STI exposure and testing for <i>N. gonorrhoeae</i>, <i>C. trachomatis</i>, and <i>T. pallidum</i> from 01/01/2023-31/10/2024. Patients were identified using ICD-10 code Z20.XX and STI testing. Doxy-PEP prescription utilization was evaluated after a dedicated doxy-PEP order was implemented with appropriate patient counseling instructions. The primary outcome was the proportion of doxy-PEP prescriptions utilized in at-risk patients; secondary outcomes were utilization of the dedicated doxy-PEP order and abnormal STI testing within 3-months of the doxy-PEP prescription. <b>Results:</b> 4234 high-risk sexual patient encounters were documented; 7.37% of patients received a doxy-PEP prescription. Of these, 29.5% were ordered utilizing a dedicated doxy-PEP order. Most patients who received a doxy-PEP prescription were Black (96.6%), men (92.6%), with a median (IQR) age of 29 (24-37) years, and had private/commercial insurance (42%). One patient had abnormal syphilis testing within 3-months of doxy-PEP prescription. <b>Conclusions:</b> These findings highlight doxy-PEP underutilization and the need for broader provider engagement and advanced antimicrobial stewardship interventions.