Table 1 Criteria employed for selection of RCTs from ClinicalTrials.gov, and patients from OPCRD

Selection criteria for RCTs

a. Recruiting patients with COPD

b. Phase III or Phase IV randomised, double-blind, placebo-controlled trial, testing

     i. Long-acting muscarinic antagonist (LAMA) OR

     ii. Long-acting β-agonist (LABA) OR

     iii. LAMA/LABA combination

c. Primary outcomes were

     i. spirometry parameter(s) OR

     ii. COPD exacerbations OR

     iii. mortality

d. Duration of treatment was ≥24 weeks post-randomisation

e. Enrolled ≥100 patients with COPD

f. Medicine was tested at licensed dose

Selection of patients with COPD from the OPCRD database

a. Quality and Outcomes Framework (QOF) approved diagnostic code of COPD, which includes the requirement for a post-bronchodilator FEV₁/FVC <0.70 [31]

b. Registered in OPCRD with data extracted from general practice at least once after 1 January 2011. The index date was defined as the date of the last data extraction

c. ≥1 year of data available prior to the index date to define RCT inclusion/exclusion criteria

d. FEV₁ and FVC recorded within 5 years of the index date

e. mMRC score recorded within 5 years of index date

f. Recorded valid blood eosinophil count ever

g. Age ≥40 years