Accuracy of a New Algorithm to Identify Asthma–COPD Overlap (ACO) Patients in a Cohort of Patients with Chronic Obstructive Airway Disease

Luis Pérez de Llano, Borja G. Cosío, Marc Miravitlles, Vicente Plaza, on behalf of the CHACOS study group

We aimed to characterize the clinical, functional and inflammatory features of patients diagnosed diagnosed with ACO according to a new algorithm and to compare them with those of other chronic obstructive airway disease (COAD) categories (asthma and COPD). ACO was diagnosed in a cohort of COAD patients in those patients with COPD who were either diagnosed with current asthma or showed significant blood eosinophilia (≥300cells/μl) and/or a very positive bronchodilator response (>400ml and >15% in FEV1). Eighty-seven (29.8%) out of 292 patients fulfilled the ACO diagnostic criteria (12.8% asthmatics who smoked <20 pack-years, 100% of asthmatics who smoked ≥20 pack-years, 47.7% of COPD with >200eosinophils/μl in blood and none with non-eosinophilic COPD). ACO, asthma and COPD patients showed no differences in symptoms or exacerbation rate. Mean pre-bronchodilator FEV1 in ACO and asthma were similar (1741 vs 1771ml), higher than in COPD (1431ml, p<0.05). DLCO was lower in ACO than in asthma (68.1 vs 84.1%) and similar to COPD (64.5%). Mean blood eosinophil count was similar in ACO and asthma (360 vs 305cells/μl) and higher than in COPD (170cells/μl). Periostin levels were similar in ACO to COPD (36.6 and 36.5IU/ml) and lower than in asthma (41.5IU/ml, p<0.05), whereas FeNO levels in ACO were intermediate. This algorithm classifies as ACO all smoking asthmatics with non-fully reversible airway obstruction and a considerable proportion of e-COPD patients, highlighting those who can benefit from inhaled corticosteroids.