Asthma-like Features and Clinical Course of Chronic Obstructive Pulmonary Disease An Analysis from the Hokkaido COPD Cohort Study

Rationale: Some patients with chronic obstructive pulmonary disease (COPD) have asthma-like features, such as significant bronchodilator reversibility, blood eosinophilia, and/or atopy, even if they are not clinically diagnosed as having asthma. However, the clinical significance of asthma-like features overlapping with COPD remains unclear. Objectives: The aim of this study was to assess the effect of asthma like features on the clinical course of patients with COPD who were adequately treated and followed-up over 10 years. Methods: A total of 268 patients with COPD who had been clinically considered as not having asthma by respiratory specialists were included in this study. The asthma-like features included in this study were bronchodilator reversibility (Delta FEV1, >= 12% and >= 200 ml), blood eosinophilia (>= 300 cells/mu l), and atopy (positive specific IgE for any inhaled antigen). The annual changes in post-bronchodilator FEV1 and COPD exacerbations were monitored during the first 5 years, and mortality was followed during the entire 10 years of the study. Measurements and Main Results: Fifty-seven subjects (21%) had bronchodilator reversibility, 52 (19%) had blood eosinophilia, and 67 (25%) had atopy. Subjects with blood eosinophilia had significantly slower annual post-bronchodilator FEV1 decline; bronchodilator reversibility and atopy did not affect the annual post-bronchodilator FEV1 decline, and none of the asthma-like features was associated with development of COPD exacerbation. Even if subjects had two or more asthma-like features, they displayed annual post-bronchodilator FEV1 declines and exacerbation rates similar to those of subjects with one or zero asthma-like features, as well as a lower 10-year mortality rate (P = 0.02). Conclusions: The presence of asthma-like features was associated with better clinical course in patients with COPD receiving appropriate treatment.