MedWire News: Patients with various subtypes of chronic obstructive pulmonary disease (COPD) differ in their response to inhaled treatment with a combined long-acting beta-agonist (LABA) and corticosteroid (ICS), Korean study results show.
“COPD is a complex and heterogeneous disorder in which a number of different pathological processes lead to recognition of patient subgroups that may have individual characteristics and distinct responses to treatment,” explain Yeon-Mok Oh (University of Ulsan College of Medicine, Seoul) and team in the journal Respiratory Medicine.
To investigate, the researchers studied 165 patients with COPD who had a post-bronchodilator ratio of FEV1/forced vital capacity ratio of less than 0.7 and a smoking history of more than 10 pack-years.
The patients were divided into four subtype groups based on the severity of emphysema and airflow obstruction: Emphysema-dominant, obstruction-dominant, mild-mixed, and severe-mixed.
Patients with the emphysema-dominant subtype had an emphysema index of more than 20% on computed tomography and an FEV1 of more than 45% of the predicted value. Patients with the obstruction-dominant subtype had an emphysema index of 20% or less and an FEV1 of less than 45% of the predicted value.
Patients with the mild-mixed subtype had an emphysema index of 20% or less and an FEV1 of more than 45% of the predicted value, and those with the severe-mixed subtype had an emphysema index of more than 20% and an FEV1 of less than 45% of the predicted value.
All the patients were assessed before and after 3 months of inhaled treatment with a combined LABA and ICS.
Analysis revealed that patients with the obstruction-dominant COPD subtype showed the greatest average increase in FEV1 (0.207 l) and those with the emphysema-dominant subtype showed the smallest, nonsignificant, increase (0.032 l). Patients with the mild-mixed, and severe-mixed COPD subtypes experienced FEV1 improvements of 0.169 l and 0.155 l, respectively.
Similarly, patients with the obstruction-dominant subtype showed the greatest reductions in dyspnea after 3 months, with an average reduction of 0.68 points on the modified Medical Research Council (MMRC) dyspnea scale, while those with the emphysema-dominant subtype showed a non-significant average reduction of just 0.16 points. Patients with the mild-mixed and severe-mixed COPD subtypes had respective reductions of 0.39 and 0.26 points on the MMRC dyspnea scale.
Oh and team conclude: “These findings indicate that the best treatment response to combined LABA and ICS may be expected in patients with the airway obstruction-dominant phenotype of COPD, who show a relatively high degree of airway reversibility. The worst responses may be expected in patients with the emphysema-dominant phenotype.”
They add: “Further studies on standardized identification of predominant phenotypes may improve our understanding of underlying COPD pathophysiology and should facilitate development of selective treatments for the complex disease labeled, in an over-simplification, as COPD.”
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