Mygind 2010.

Study characteristics
Methods	Design: randomised, placebo‐controlled, double‐blind study Duration: 156 weeks Location: NR
Participants	Population: 575 adults with moderate to severe COPD were randomly assigned to azithromycin (n = 287) or placebo (n = 288) Baseline characteristics: age > 50 years; moderate to severe COPD; % FEV₁ predicted < 60; previous documented allergies to macrolides; clinical history of lung cancer, asthma, or bronchiectasis; exacerbation history: not reported Inclusion criteria: ≥ 1 admission to hospital with an exacerbation of COPD; ex‐smoker or current smoker Exclusion criteria: end‐stage COPD patients (if not expected to survive over 3 years) or bedridden patients; history of asthma, bronchiectasis, or other significant respiratory disease; history of azithromycin allergy; heart, liver, or renal insufficiency; already receiving prophylactic antibiotic
Interventions	Azithromycin 500 mg daily for 3 days every month, for 36 months Placebo daily for 3 days every month, for 36 months Allowed co‐medications: not reported
Outcomes	Rate of decline in lung function (FEV₁), frequency of exacerbation, health‐related quality of life, adverse events, mortality, duration of exacerbations, number of days of hospitalisation, frequency of hospitalisation
Notes	Funding: not reported Identifier: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised but paucity of data was available on sequence generation
Allocation concealment (selection bias)	Unclear risk	This was not explained well
Blinding of participants and personnel (performance bias) All outcomes	Low risk	This was a double‐blind study
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unknown. This study was double‐blind, but it is unclear whether outcome assessors were blinded
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	All outcome data were presented. Only 55% completed 3 years
Selective reporting (reporting bias)	Low risk	All pre‐specified outcomes were reported
Other bias	Unclear risk	This was a conference presentation ‐ not a full publication. Attempts to contact study authors were not successful. Only limited data are available for evaluation of the risk of bias