Assessing Disparities in DoxyPEP Implementation Using the DoxyPEP-to-Need Ratio: Evidence from an HIV Primary Care Clinic in Seattle, WA

Abstract

Background: Doxycycline post-exposure prophylaxis (doxyPEP) is effective in preventing STIs among men who have sex with men and transgender women, but little is known about its implementation. We applied the doxyPEP-to-need ratio (DPnR), measuring the number of people prescribed doxyPEP divided by people diagnosed with an STI, to explore inequities in doxyPEP implementation at an HIV primary care clinic in Seattle, WA.Methods: We conducted a repeat cross-sectional analysis comparing doxyPEP prescriptions relative to incident STI diagnoses. We calculated the proportion of people with an STI who received doxyPEP, as well as annual DPnRs, stratified across patient race and ethnicity, age, primary language, and type of insurance. Patient zip code of residence was used in an ecological analysis evaluating the DPnR by population-level poverty and educational attainment. Results: From 2023 to 2025, The proportion of people with an STI receiving doxyPEP rose from 19.6% to 51.9%, and the overall DPnR increased nearly four-fold. In 2025, White, Hispanic, and Asian individuals had the highest DPnRs (1.89, 1.84, 1.90, respectively), while Black (1.27) and Indigenous (1.13) individuals had the lowest. Compared with English speakers, Spanish speakers had 20% more and non-English/non-Spanish speakers 22% fewer doxyPEP prescriptions per STI. People with public insurance had a lower DPnR than those with private or no insurance. Geographic areas with higher poverty and lower educational attainment had lower DPnR. The DPnR standard deviation increased over time across race and ethnicity, age, language, and insurance groups, indicating growing inequity in doxyPEP prescribing patterns. Conclusion: We found widening disparities in doxyPEP use relative to STI burden, particularly among Black, Indigenous, and non-English/non-Spanish speaking individuals, highlighting the importance of prioritizing minority populations in doxyPEP implementation efforts.