Supplementary Material for: Risk Factors of Rapid FEV1 Decline in a Real-World Chronic Obstructive Pulmonary Disease Cohort

Background: Rapid forced expiratory volume in 1 s (FEV1) decliners have been considered a unique subgroup of patients with chronic obstructive pulmonary disease (COPD). Rapid FEV1 decline manifests early and is associated with poor prognosis. This necessitates the pre-emptive identification of risk factors for rapid FEV1 decline. Objectives: We aimed to determine the risk factors and clinical outcomes in patients with COPD. Methods: This longitudinal, observational study was based on the Korea COPD Subgroup Study cohort (NCT02800499) from January 2012 to December 2019 across 54 medical centers in South Korea. Eligible patients were followed up for 3 years with serial spirometric tests. We calculated the annualized percentage change in FEV1 from baseline. Rapid decliners were defined as the quartile of patients with the highest annualized percentage FEV1 decline. Results: Of the 518 patients, 130 were rapid decliners who lost 6.2%/year and 100 mL/year of FEV1. The multivariable logistic regression identified male sex, current smoking, blood eosinophil count 1 decline. Among rapid decliners, the lung function deteriorated more rapidly in current smokers and patients with severe dyspnea, while triple combination therapy attenuated lung function decline in comparison with mono-bronchodilator therapy. Rapid decliners had a higher rate of severe exacerbation than nonrapid decliners (0.2/year vs. 0.1/year, p value = 0.032). Conclusions: We identified the independent risk factors for rapid FEV1 decline. This information may assist physicians in the early detection and pertinent management of rapid decline among patients with COPD.