Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Adverse effects
[30] Systematic review	807 people 2 RCTs in this analysis	Proportion of people withdrawing from a study because of adverse effects with tiotropium with salmeterol Absolute results not reported	OR (salmeterol v tiotropium) 2.16 95% CI 1.36 to 3.43 P = 0.001 No further information on adverse effects reported	Moderate effect size	tiotropium