Summary studies included in review

Type of studyPublications found in the search and considered in the review
Meta-analysis or systematic review4 (3 meta-analyses, 1 systematic review)
Randomised controlled trial53 (765 participants in total of which 682 people with asthma and 83 with reversible airways disease)
Non-randomised trial31 (106 915 participants in total of which 63 763 were asthma alone, 43 152 were asthma or COPD)
Literature review12 (9 asthma, 1 obstructive lung disease, 1 reversible airways disease and 1 on adverse reactions to β-blockers)
Other27 (8 case reports, 7 murine models, 7 guinea pig models, 4 opinion articles, 1 questionnaire)

Studies that could be allocated to two categories are included in the highest tier (for example, meta-analysis above non-randomised trial).