Different therapeutic responses in chronic obstructive pulmonary disease subgroups

SETTING: Eleven referring hospitals in South Korea.OBJECTIVE: To compare therapeutic responses in chronic obstructive pulmonary disease (COPD) subgroups, classified by diffusing capacity of the lung for carbon monoxide (DLCO) and lung volume.DESIGN: A total of 130 stable male COPD patients were classified into four subgroups according to baseline DLCO and residual volume/total lung capacity (RV/TLC) ratio. We compared therapeutic responses to short acting β2-agonist (SABA) and 3-month combined inhalation of long-acting β2-agonist (LABA) and corticosteroid among patients with these subgroups.RESULTS: Among the 130 COPD patients, 41 (31.5%) had normal DLCO and RV/TLC, 28 (21.5%) low DLCO and normal RV/TLC, 31 (23.8%) normal DLCO and high RV/TLC, and 30 (23.1%) low DLCO and high RV/TLC. The normal DLCO/high RV/TLC subgroup showed a significantly larger flow response (changes in forced expiratory volume in 1 s) to salbutamol than the normal DLCO/RV/TLC subgroups, and a larger volume response (changes in forced vital capacity) than the two normal RV/TLC subgroups. The normal DLCO/high RV/TLC subgroup also showed significantly larger flow and volume response to 3-month combined inhalation of LABA and corticosteroid than the two normal RV/TLC subgroups.CONCLUSION: COPD subgroups classified by DLCO and RV/TLC may have different pulmonary function responses to pharmacological treatment.