Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
COPD exacerbations
[76] Systematic review	746 people 10 RCTs in this analysis	Proportion of people with an exacerbation 269/382 (70%) with prophylactic antibiotics 285/364 (78%) with placebo	RR 0.91 95% CI 0.84 to 0.99 The results of the review should be interpreted with caution (see comment)	Small effect size	prophylactic antibiotics
[76] Systematic review	779 people 8 RCTs in this analysis	Number of exacerbations per person per year with prophylactic antibiotics with placebo Absolute results not reported	WMD –0.15 95% CI –0.34 to +0.04 The results of the review should be interpreted with caution (see comment)		Not significant
[77] RCT	109 people with COPD, FEV1 30% to 70% expected	Number of moderate to severe exacerbations 12 months 81 exacerbations in 53 people with erythromycin 250 mg twice daily 125 exacerbations in 56 people with placebo	RR 0.65 95% CI 0.49 to 0.86 P = 0.003	Small effect size	prophylactic antibiotics