The Cochrane Airways Group has reviewers in 21 countries world-wide. Most (67%) of the completed reviews are in asthma, with 46% of all reviews in chronic asthma. The asthma reviews tend to include a slightly larger number of trials than those in COPD although on average, the COPD RCTs tend to include more patients. On average, the reviews include data from over 750 patients and they examine the effects of interventions on variety of outcome measures.