Commentary

Acute otitis externa, an infection of the external auditory canal, is associated with exposure to warm humid climates, swimming, and aggressive cleaning of the ear canal.¹ It is a common disease in primary care, usually treated with ear drops containing antibiotics with steroids; however, the optimal treatment has not been established. The study by van Balen et al is the first large study of acute otitis externa that examined cure rates at 7 days and recurrence after symptom resolution. Based on the findings, the authors recommend that acetic acid drops alone should no longer be used to treat adults with acute otitis externa.

Methodological strengths of this study include recruitment of patients from 47 general practices, concealed allocation of patients, blinding of patients and clinicians, training of general practitioners in diagnosing and treating acute otitis externa, and inclusion of important clinical endpoints, such as speed of recovery and symptom recurrence up to 42 days after treatment initiation. Adjustment of the primary and secondary outcomes for differences in baseline characteristics improved the rigour of the study. Confidence intervals around odds ratios reported in the study and around the relative benefit increases and the relative risk reductions reported in the table of the EBN abstract indicate a lack of precision that would have been improved with a larger sample size.

The study makes a strong case for the use of steroids combined with either acetic acid or antibiotics for treatment of acute otitis externa. Caution should be exercised when applying these findings to patients with comorbid conditions because this study predominantly included healthy adults. The results are particularly relevant to nurse practitioners working in primary healthcare and ear-nose-throat clinical settings.