Impact of Changes in Chlamydia Treatment Guidelines on Recurrent/Persistent Rectal Chlamydia trachomatis Infections.

INTRODUCTION: Prior to 2021, the US Centers for Disease Control and Prevention (CDC) recommended either doxycycline or azithromycin as first-line treatments for Chlamydia trachomatis (CT). By 2016, there was evidence showing that doxycycline was more effective than azithromycin for the treatment of rectal CT. This motivated the Public Health-Seattle & King County Sexual Health Clinic to update their clinic's protocol to treat rectal CT with exclusively doxycycline in mid-2016. The CDC later recommended this in July 2021. METHODS: Leveraging health records from the clinic, we performed a controlled interrupted time series analysis to evaluate the impact of updated treatment guidelines at the clinic on recurrent/persistent (RP) rectal chlamydia (RP-CT) infections among men who have sex with men using RP rectal gonorrhea (RP-GC) as a control outcome. We also evaluated if there were patient demographic and behavioral correlates associated with receipt of azithromycin before and after the change in clinic guidelines. RESULTS: Our analysis revealed a significant relative trend change between RP-CT and RP-GC when comparing the period of full implementation to preimplementation, showing a 16.9% greater reduction in the quarterly trend of RP-CT cases compared to RP-GC cases. Self-identifying as White and with human immunodeficiency virus were positively associated with receiving azithromycin for treatment of rectal CT after the change in guidelines. CONCLUSIONS: The significant reduction in the trend change for RP-CT versus RP-GC when comparing the fully implemented period of exclusive doxycycline to the preimplementation period demonstrates the impact of the new treatment guidelines in reducing incidence of RP-CT infections.