Clinical Outcomes in Patients With COPD With Disease Stability: Data from the Korea COPD Subgroup Study Cohort

Background: COPD is a heterogeneous disease with progressive airflow limitation. Despite therapeutic advances, current treatments poorly halt COPD progression. Disease stability (DS) is a proposed treatment goal, but its clinical significance remains uncertain. Research Question: What are the differences in lung function decline, exacerbation risk, and mortality between patients with COPD with and without DS? Study Design and Methods: This study analyzed data from the Korean COPD Subgroup Study, a nationwide prospective cohort of patients with COPD in South Korea. Participants were ≥ 40 years of age and had a postbronchodilator FEV₁/FVC ratio < 0.70. Ten-year all-cause mortality data were obtained from national death records and merged with cohort data. DS (+) was defined as the absence of moderate-to-severe exacerbations, no decline in FEV₁, and no worsening of the St. George's Respiratory questionnaire score during the first year. Clinical outcomes were compared between patients with DS (+) and patients without DS (+), who were classified as DS (–). Results: Among 1,639 patients analyzed, 147 (9.0%) achieved DS (+), whereas 1,492 (91.0%) were classified as DS (–). Baseline characteristics were similar between groups. Compared with the DS (–) group, the DS (+) group exhibited significantly lower rates of moderate-to-severe exacerbations (incidence rate ratio, 0.30; P = .033) and severe exacerbations (incidence rate ratio, 0.26; P = .002). Paradoxically, the annual decline in FEV₁ was greater in the DS (+) group (–45.8 vs –10.3 mL/y; P < .001). Multivariable Cox regression analysis demonstrated that DS (+) status was independently associated with a significantly reduced risk of all-cause mortality (adjusted hazard ratio, 0.56; P = .036). Interpretation: Patients with COPD with DS (+) showed reduced exacerbations and mortality. These findings support DS as a clinically meaningful and achievable treatment target in COPD, with potential utility in guiding personalized disease management.