KOrea COpd Subgroup Registry and Subtype Research

This study is a multicentered, observational study of the patients with COPD who were enrolled in 45 tertiary and university-affiliated hospitals from December 2012 to now. The initial evaluation for all patients includes pulmonary function tests (PFT), 6-min walk distance (6MWD), COPD Assessment Test (CAT), modified Medical Research Council (mMRC) dyspnea scale, and the COPD-specific version of St. George's Respiratory Questionnaire (SGRQ-C), exacerbations in the previous 12 months, smoking status, patient-reported education level, medications and comorbidities. Pulmonary function tests (PFTs) are performed every 6 months and CAT, mMRC and SGRQ-C are evaluated every 6 months and 6 min walt test is performed every years during the whole period of study. All of the data were reported using case-report forms (CRFs) which are completed by physicians or trained nurses, and the patients are to be evaluated at regular 6-month intervals after the initial examination.