Influence of the duration of penicillin prescriptions on outcomes for acute sore throat in adults: the DESCARTE prospective cohort study in UK general practice.

Background: Guidelines recommend 10-day treatment courses for acute sore throat, but shorter courses may be used in practice.

Aim: To determine whether antibiotic duration predicts adverse outcome of acute sore throat in adults in routine care.

Design And Setting: A secondary analysis of the DESCARTE (Decision rule for the Symptoms and Complications of Acute Red Throat in Everyday practice) prospective cohort study of 12 829 adults presenting in UK general practice with acute sore throat.

Method: A brief clinical proforma was used to collect symptom severity and examination findings at presentation. Outcomes were collected by notes review, a sample also completed a symptom diary. The primary outcome was re-consultation with new/non-resolving symptoms within 1 month. The secondary outcome was 'global' poorer symptom control (longer than the median duration or higher than median severity).

Results: Antibiotics were prescribed for 62% (7872/12 677) of participants. The most commonly prescribed antibiotic was phenoxymethylpenicillin (76%, 5656/7474) and prescription durations were largely for 5 (20%), 7 (57%), or 10 (22%) days. Compared with 5-day courses, those receiving longer courses were less likely to re-consult with new or non-resolving symptoms (5 days 15.3%, 7 days 13.9%, 10 days 12.2%, 7-day course adjusted risk ratio (RR) 0.92 [95% confidence interval [CI] = 0.76 to 1.11] and 10-days RR 0.86 [95% CI = 0.59 to 1.23]) but these differences did not reach statistical significance.

Conclusion: In adults prescribed antibiotics for sore throat, the authors cannot rule out a small advantage in terms of reduced re-consultation for a 10-day course of penicillin, but the effect is likely to be small.