Effect of a widespread reduction in treatment duration for group A streptococcal pharyngitis on outcomes and household transmission.

Backgroundthe optimal treatment duration for group A streptococcal pharyngitis (GAS-P) is debated. Shorter courses appear inferior for pharyngeal GAS eradication, however the effect of this on household transmission is uncertain. In 2022 a laboratory reporting change drove reduced treatment durations for GAS-P in our region. This study sought to assess the effect of this on outcomes. Methodspositive throat swab cultures (TSC) for GAS from two years pre-change until 21 months post-change were matched to antibiotic dispensing data. Logistic models were fitted to examine associations between treatment duration and 30-day repeat antibiotic treatment, repeat GAS-positive TSC, and hospitalisation with complications; 90-day incidence of rheumatic fever; 30-day incident household GAS-P cases. Results865 patients pre-change and 1604 post-change were included. Pre-change 32.8% received [&le;]7 days treatment, versus 60.0% post-change (p<0.01). There were no significant differences across any outcome measure at a population level between periods. When the post-change period was examined specifically, no significant differences occurred for any outcome measure for patients receiving five- or seven-days of antibiotics versus ten-days. Patients receiving no antibiotics also had similar outcomes, except for significantly higher odds of 30-day household cases (aOR 2.93, 95%-CI 1.44-5.96, p<0.01). Conclusionsshorter treatment durations driven by a change in laboratory reporting resulted in no detectable change in GAS-P outcomes, except for more common household transmission in those receiving no treatment.