Roy 2014.

Methods	Randomised, single‐blind, placebo‐controlled, parallel, single‐centre. PP analysis. Duration 6 months Followed up every month
Participants	80 outpatients age > 40, stable mild to moderate COPD, smoking history at least 10 pack‐years. Exclusions: those with asthma, lung cancer, cardiomyopathy, LVRS or transplant, or on LTOT or corticosteroids. Mean age 61; 89% male. Total 20 dropouts, evenly matched between groups
Interventions	NAC 600 mg twice daily or placebo. Both groups received a bronchodilator Deriphylline Retard 150 mg in addition
Outcomes	Symptoms (cough, dyspnoea, sputum), spirometry, Hb, adverse events
Notes	Indian Funding source not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	No details on this, except it was a "simple method"
Allocation concealment (selection bias)	High risk	Single‐blind study; few details on allocation or concealment of sequence given
Blinding of participants and personnel (performance bias) All outcomes	High risk	No details on match between placebo and NAC, or on who performed measurements; sIngle‐blind
Blinding of outcome assessment (detection bias) All outcomes	High risk	SIngle‐blind study
Incomplete outcome data (attrition bias) All outcomes	High risk	25% dropout rate (20/80); numbers and reasons per arm not given
Selective reporting (reporting bias)	Unclear risk	Spirometric data reported in units that read "total count"