Background: Antibiotic treatment of acute bronchitis, which is one of the most common illnesses seen in primary care, is controversial. Most clinicians prescribe antibiotics in spite of expert recommendations against this practice.
Objectives: The objective of this review was to assess the effects of antibiotic treatment for patients with a clinical diagnosis of acute bronchitis.
Search strategy: We searched MEDLINE, EMBASE, reference lists of articles and the authors' personal collections up to 1996, and Scisearch from 1989 to 1996; we also wrote to study authors and drug manufacturers. An updated search of the Cochrane Controlled Trials Register and MEDLINE was conducted in 2000.
Selection criteria: Randomised trials comparing any antibiotic therapy with placebo in acute bronchitis or acute productive cough without other obvious cause in patients without underlying pulmonary disease.
Data collection and analysis: At least two reviewers extracted data and assessed trial quality. Authors were contacted for missing data.
Main results: Nine trials involving over 750 patients aged eight to over 65 and including smokers and non-smokers were included. The quality of the trials was variable. A variety of outcome measures were assessed. Overall, patients receiving antibiotics had better outcomes than did those receiving placebo. At a follow-up visit, they were less likely to have a cough (relative risk 0.64, 95% confidence interval 0.49 to 0.85; number needed to treat 5, 95% CI 3 to 14), show no improvement on physician assessment (RR 0.52, 95% CI 0.31 to 0.87; NNT 14, 95% CI 8 to 50), or have abnormal lung findings (RR 0.48, 95% CI 0.26 to 0.89; NNT 11, 95% CI 6 to 50); and had shorter durations of cough (weighted mean difference 0.58 days, 95% CI 0.01 to 1.16 days), productive cough (WMD 0.52 days, 95% CI 0.01 to 1.03 days), and feeling ill (WMD 0.58 days, 95% CI 0.00 to 1.16 days). There were no significant differences regarding the presence of night cough, productive cough, or activity limitations at follow-up, or in the mean duration of activity limitations. The benefits of antibiotics were less apparent in a sensitivity analysis that included data from two other studies of patients with upper respiratory tract infections with productive cough. Antibiotic-treated patients reported significantly more adverse effects (RR 1.48, 95% CI 1.02 to 2.14; number needed to harm 17, 95% CI 9 to 100) such as nausea, vomiting, headache, skin rash or vaginitis.
Reviewer's conclusions: Overall, antibiotics appear to have a modest beneficial effect in patients who are diagnosed with acute bronchitis. The magnitude of this benefit, however, is similar to that of the detriment from potential adverse effects. Furthermore, patients with other symptoms of the common cold who have been ill for less than one week are not likely to have any benefit from antibiotics.