| Methods |
Randomised, double‐blind, placebo‐controlled, parallel, multi‐centre (10 centres). PP analysis. Duration "long term" means 8 months |
| Participants |
313 outpatients with COPD (diagnostic criteria not clear). Mean age 57 years; 60% male. Mean FEV₁ 60% predicted. 18 dropped out |
| Interventions |
NAC 600 mg daily or placebo |
| Outcomes |
Exacerbations, severity of exacerbations, time to first exacerbation, days sick, lung function, participant symptoms, adverse effects |
| Notes |
European. COPD, not chronic bronchitis. BREATHE study. Published in abstract form only. Zambon provided more information. Study never published in full |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Information not available |
| Allocation concealment (selection bias) |
Unclear risk |
Information not available |
| Blinding of participants and personnel (performance bias)
All outcomes |
Low risk |
Double‐blind |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Double‐blind |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
12/159 (8%) dropped out of the intervention arm and 6/154 (4%) dropped out of the placebo arm. Reasons for dropout not reported, but overall low rate of attrition |
| Selective reporting (reporting bias) |
High risk |
Information not available |
