Fig. 1

Flowchart illustrating patient selection. ^*Body mass index, % predicted post-bronchodilator forced expiratory volume in 1 s (FEV₁), exacerbation history during the previous year, the modified Medical Research Council dyspnea score, and the St. George’s respiratory questionnaire for COPD score at baseline

COPD chronic obstructive pulmonary disease, KOCOSS Korean COPD Subgroup Study, KOLD Korean Obstructive Lung Disease.