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

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.

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.

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.

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.