Peritonsillar Abscess and Antibiotic Prescribing for Respiratory Infection in Primary Care: A Population-Based Cohort Study and Decision-Analytic Model

PURPOSE To quantify the risk of peritonsillar abscess (PTA) following consultation for respiratory tract infection (RTI) in primary care. METHOD A cohort study was conducted in the UK Clinical Practice Research Datalink including 718 general practices with 65,681,293 patient years of follow-up and 11,007 patients with a first episode of PTA. From a decision tree, Bayes theorem was employed to estimate both the probability of PTA following an RTI consultation if antibiotics were prescribed or not, and the number of patients needed to be treated with antibiotics to prevent 1 PTA. RESULTS There were 11,007 patients with PTA with age-standardized incidence of new episodes of PTA of 17.2 per 100,000 patient years for men and 16.1 for women; 6,996 (64%) consulted their practitioner in the 30 days preceding PTA diagnosis, including 4,243 (39%) consulting for RTI. The probability of PTA following an RTI consultation was greatest in men aged 15 to 24 years with 1 PTA in 565 (95% uncertainty interval 527 to 605) RTI consultations without antibiotics prescribed but 1 in 1,139 consultations (1,044 to 1,242) if antibiotics were prescribed. One PTA might be avoided for every 1,121 (975 to 1,310) additional antibiotic prescriptions for men aged 15 to 24 years and 926 (814 to 1,063) for men aged 25 to 34 years. The risk of PTA following RTI consultation was smaller and the number needed to treat higher at other ages and risks were lower in women than men. CONCLUSIONS The risk of PTA may be lower if antibiotics are prescribed for RTI but even in young men nearly 1,000 antibiotic prescriptions may be required to prevent 1 PTA case. We caution that lack of randomization and data standardization may bias estimates.