Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
COPD exacerbations
[29] Systematic review	1399 people 3 RCTs in this analysis	COPD exacerbations 12 weeks with short-acting anticholinergic (ipratropium) plus short-acting beta2 agonist with short-acting beta2 agonist alone Absolute results not reported	RR 0.68 95% CI 0.51 to 0.91	Small effect size	short-acting anticholinergic plus short-acting beta2 agonist
Symptom severity
[44] Systematic review	1529 people 5 RCTs in this analysis	Dyspnoea component of the Chronic Respiratory Disease Questionnaire (CRQ) 85 days with ipratropium plus short-acting beta2 agonist with short-acting beta2 agonist alone Absolute results not reported	WMD +0.01 95% CI –0.06 to +0.08 P = 0.8		Not significant