Defining the Asthma-COPD Overlap Syndrome in a COPD Cohort

BACKGROUND: Asthma-COPD overlap syndrome (ACOS) has been recently described by international guidelines. A stepwise approach to diagnosis using usual features of both diseases is recommended although its clinical application is difficult. METHODS: To identify patients with ACOS, a cohort of well-characterized patients with COPD and up to 1 year of follow-up was analyzed. We evaluated the presence of specific characteristics associated with asthma in this COPD cohort, divided into major criteria (bronchodilator test > 400 mL and 15% and past medical history of asthma) and minor criteria (blood eosinophils > 5%, IgE > 100 IU/mL, or two separate bronchodilator tests > 200 mL and 12%). We defined ACOS by the presence of one major criterion or two minor criteria. Baseline characteristics, health status (COPD Assessment Test [CAT]), BMI, airflow obstruction, dyspnea, and exercise capacity (BODE) index, rate of exacerbations, and mortality up to 1 year of follow-up were compared between patients with and without criteria for ACOS. RESULTS: Of 831 patients with COPD included, 125 (15%) fulfilled the criteria for ACOS, and 98.4% of them sustained these criteria after 1 year. Patients with ACOS were predominantly male (81.6%), with symptomatic mild to moderate disease (67%), who were receiving inhaled corticosteroids (63.2%). There were no significant differences in baseline characteristics, and only survival was worse in patients with non-ACOS COPD after 1 year of follow-up (P <.05). CONCLUSIONS: The proposed ACOS criteria are present in 15% of a cohort of patients with COPD and these patients show better 1-year prognosis than clinically similar patients with COPD with no ACOS criteria.