Nine randomised trials (total n=774, including over 276 smokers) were included.
No studies specifically addressed antibiotic use in smokers or reported subgroup data for smokers. The results for smokers were as reported by the original study authors.
The mean quality score was 3.9 (range: 3 to 5) out of a maximum of 5, indicating some deficiencies in blinding, randomisation or follow-up.
Antibiotics showed no overall benefit in five of the trials. In four of these trials, smoking status did not alter the lack of response to antibiotics, with one trial showing a trend towards reduced symptom scores only among nonsmokers receiving erythromycin and a trend toward higher symptom scores among smokers receiving erythromycin. One trial did not stratify by smoking status.
In another trial, TMP-SMX resulted in less frequent cough over 7 days in all patients treated (93% for TMP-SMX treated group versus 99% in placebo treated group; one-tailed P=0.05), but not among smokers.
The remaining three trials reported decreased duration of daytime cough, days off work, and sputum production score for antibiotic-treated patients. For all three trials, smoking status neither enhanced nor diminished the patients' response to antibiotics.
In the seven trials where they were reported, adverse effects averaged 11% (range among trials: 0 to 37) in placebo-treated patients and 16% (range among trials: 6 to 36) in antibiotic-treated patients (P=0.08). The most frequent adverse effects were gastrointestinal upset, nausea and vomiting. No trial stratified adverse effects by smoking status.