Distribution and clinical characteristics of chronic obstructive pulmonary disease patients based on a new classification: Insights from a real-world cohort study

초록

Background and Aims: Cigarette smoking is one of the most important risk factor for developing chronic obstructive pulmonary disease (COPD). However, risk factors unrelated to cigarette smoking are increasingly responsible for the burden of COPD. Lancet commissions on COPD recommended that COPD be classified into types based on five main risk factors driving the disease: genetics, early-life events, pulmonary infections, tobacco smoke exposure, and pollution.1 In the present study, we aim to apply the proposed suggestions to real-world cohort patients. Methods: Patients with COPD were prospectively enrolled into the Korean COPD subgroup study (KOCOSS) cohort, a multicenter cohort study of COPD patients recruited from 54 medical centers in South Korea. Results: Of the 3477 COPD patients registered in the KOCOSS database between April 2012 and June 2022. Among these patients, there were 52 patients with type 2, 1293 patients with type 3, 2931 patients with type 4, and 2221 patients with type 5. In addition, 84 patients were included who did not fit any type. Patients in type 4 were the most common, and 2406 patients belonged to two or more types. The proportion of patients experiencing moderate to severe exacerbations during the prospective follow up 1 year was 42.9%, 43.9%, 41.0%, and 40.2% for types 2, 3, 4, and 5, respectively. Also, we compared the characteristics among non-overlapping patients. Severe exacerbations were most frequent in patients with type 3 only (0.038). Conclusion: Many COPD patients were affected by multiple factors simultaneously. Therefore, it is important to consider not only smoking history but also other potential risk factors when evaluating COPD patients. This study can be considered as a foundation for future COPD research using the new classification system.