Measuring Doxycycline Postexposure Prophylaxis Use Relative to Sexually Transmitted Infection Rates at a San...

Doxycycline postexposure prophylaxis (doxyPEP) must reach people at high risk for bacterial sexually transmitted infections (STIs) to reduce STI rates and inequities. PrEP-to-Need Ratios (PNR) identified inequities in pre-exposure prophylaxis (PrEP) by measuring PrEP prescriptions relative to human immunodeficiency virus (HIV) rates. We evaluated a novel application of the PNR framework to doxyPEP for STIs to identify inequities in doxyPEP by race/ethnicity.

Using cross-sectional clinical and surveillance datasets, we compared doxyPEP use relative to STI diagnoses, a measure of need, among patients eligible for a doxyPEP prescription seen at San Francisco City Clinic in the 3 years following the release of citywide doxyPEP guidelines (October 2022). "Use" was defined as having received a prescription for or self-reporting taking doxyPEP. "Need" was the number of unique patients diagnosed with at least one chlamydia, gonorrhea, or early syphilis infection. The doxyPEP-to-Need Ratio (dPNR) was calculated as the ratio of "use" to "need" and was compared by race/ethnicity and year.

By the end of the evaluation period (September 2025), doxyPEP use was highest among eligible Latine patients (76%), then Asian (71%) and White (67%) patients, and lowest among Black patients (59%). However, because Latine and Black patients had similarly higher rates of doxyPEP-preventable infections compared with Asian and White patients, dPNR was consistently higher for Asian and White patients compared with Latine and Black patients. Latine and Black patients experienced persistently lower doxyPEP use relative to need compared with White patients.

The dPNR is a novel and useful metric for identifying actionable inequities in doxyPEP access for STI prevention.