Trends in Chlamydia trachomatis Treatment Prescribing Practices in King County, Washington, 2010 – 2018

Chlamydia trachomatis (CT) is the most commonly reported bacterial sexually transmitted infection in the United States. In 2021, the CDC updated its CT treatment guidelines from equally recommending either azithromycin (1 gram as a single dose) or doxycycline (100mg twice daily for 7 days) to only recommending doxycycline as first line treatment after 2021. We conducted a trends analysis using the Washington STD surveillance database to understand which patients and providers may be most impacted by the guideline change. We included all female cases of urogenital CT aged >15 years who resided in King County and were diagnosed from 2010-2018. Our dataset contained information on demographic factors, sexual history, clinical features, diagnosing facility, year, and treatment regimen. We conducted descriptive analyses and Poisson regression analyses to examine the distribution of azithromycin use and associated risk factors. There were 36,830 cases of female urogenital CT during the study period; over 90% of cases received azithromycin, with the proportion of azithromycin use increasing in all facilities from 2010 to 2018. Five of the eight facility type groups were prescribing azithromycin to more than 95% of their cases in 2018. Cases who were younger or cases of color were more likely to receive azithromycin (versus doxycycline) compared to older and white cases respectively. These findings suggest that a substantial shift in prescribing practices will be needed to change from the observed azithromycin use to the newly recommended doxycycline regime. Patients who continue to receive azithromycin may be at higher risk for CT reinfection and subsequent severe outcomes. The differences in prescribing practices by facility and patient characteristics highlight the need for targeted and multifaceted educational campaigns to encourage a transition to doxycycline use.