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: In this updated review, we searched the Cochrane Central Register of Controlled trials (CENTRAL) (The Cochrane Library Issue 2, 2004); MEDLINE (January 1966 to March 2004); EMBASE (January 2000 to December 2003); SciSearch from 1989 to 2004; reference lists of articles and the authors' personal collections up to 1996, and also wrote to study authors and drug manufacturers. EMBASE has previously been searched from 1974 to 2000).
Selection criteria: Randomised controlled 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 in the primary analysis. 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 (RR) 0.64, 95% confidence interval (CI) 0.49 to 0.85; number-needed-to-treat (NNT) 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 (weighted mean difference (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. There was a non significant trend towards an increase in adverse effects in the antibiotic group, relative risk (RR) 1.22 (95% CI 0.94 to 1.58).
Reviewers' 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.