Factors Associated with the Discrepancy between Exercise Capacity and Airflow Limitation in Patients with Chronic Obstructive Pulmonary Disease

• Published in: Tuberculosis and respiratory diseases Vol. 87; no. 2; pp. 155 - 164
• Main Authors: Tae Hoon Kim, I Re Heo, Na Young Kim, Joo Hun Park, Hee-young Yoon, Ji Ye Jung, Seung Won Ra, Ki-suck Jung, Kwang Ha Yoo, Ho Cheol Kim
• Format: Journal Article
• Language: Korean
• Published: 대한결핵 및 호흡기학회 01-04-2024
• Subjects: 6-Minute Walk Distance; Chronic Obstructive Pulmonary Disease; Exercise Capacity; Forced Expiratory Volume in 1 Second; Forced Expiratory Volume in 1 Second; Chronic Obstructive Pulmonary Disease; Exercise Capacity; 6-Minute Walk Distance
• ISSN: 1738-3536; 2005-6184

Background: Exercise capacity is associated with lung function decline in chronic obstructive pulmonary disease (COPD) patients, but a discrepancy between exercise capacity and airflow limitation exists. This study aimed to explore factors contributing to this discrepancy in COPD patients.
Methods: Data for this prospective study were obtained from the Korean COPD Subgroup Study. The exercise capacity and airflow limitation were assessed using the 6-minute walk distance (6-MWD; m) and forced expiratory volume in 1 second (FEV 1 ). Participants were divided into four groups: FEV 1 >50%+6-MWD >350, FEV 1 >50%+6-MWD ≤350, FEV 1 ≤50%+6-MWD >350, and FEV 1 ≤50%+6-MWD ≤350 and their clinical characteristics were compared.
Results: A total of 883 patients (male:female, 822:61; mean age, 68.3±7.97 years) were enrolled. Among 591 patients with FEV 1 >50%, 242 were in the 6-MWD ≤350 group, and among 292 patients with FEV 1 ≤50%, 185 were in the 6-MWD >350 group. The multiple regression analyses revealed that male sex (odds ratio [OR], 8.779; 95% confidence interval [CI], 1.539 to 50.087; p=0.014), current smoking status (OR, 0.355; 95% CI, 0.178 to 0.709; p=0.003), and hemoglobin levels (OR, 1.332; 95% CI, 1.077 to 1.648; p=0.008) were significantly associated with discrepancies in exercise capacity and airflow limitation in patients with FEV 1 >50%. Meanwhile, in patients with FEV 1 ≤50%, diffusion capacity of carbon monoxide (OR, 0.945; 95% CI, 0.912 to 0.979; p=0.002) was significantly associated with discrepancies between exercise capacity and airflow limitation.
Conclusion: The exercise capacity of COPD patients may be influenced by factors other than airflow limitation, so these aspects should be considered when assessing and treating patients.