Clinical Severity, Multidimensional Assessment, and Functional Impairment in COPD Patients Undergoing Specialized Functional-Capacity Assessment

Background/Objectives: Chronic obstructive pulmonary disease (COPD) causes functional consequences that may not be fully captured by conventional measures of disease severity. Methods: This retrospective cross-sectional study explored associations between clinical-functional characteristics and limitations in activities of daily living (ADL) among 184 patients with COPD undergoing specialized functional-capacity evaluation. Associations of clinical severity, forced expiratory volume in one second (FEV1), dyspnea, exercise capacity, and the BODE index with ADL limitation were evaluated using multivariable ordinal regression models. Results: In exploratory adjusted analyses, lower FEV1 (adjusted OR 0.87, 95% CI 0.81–0.94), greater dyspnea severity (mMRC: adjusted OR 32.09, 95% CI 6.67–154.46), and poorer exercise capacity (6MWT impairment score: adjusted OR 6.77, 95% CI 1.66–27.56) were associated with increasing ADL limitation. In a separate exploratory adjusted model, GOLD C (adjusted OR 5.14, 95% CI 1.65–16.02) and GOLD D (adjusted OR 33.65, 95% CI 8.15–138.88) were associated with greater functional limitation compared with GOLD A. The BODE index was also strongly associated with increasing ADL limitation. Conclusions: Functional impairment in COPD is multidimensional and cannot be adequately characterized by airflow limitation or disease classification alone. Integrating physiological, symptomatic, exercise, and functional measures may provide a more comprehensive characterization of disease impact in specialized functional-capacity evaluation.