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

Abstract

Objectives: 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).

Methods: 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).

Results: 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.

Conclusion: 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.

Keywords: Asma; Asthma; Asthma-chronic obstructive pulmonary disease overlap; Chronic obstructive pulmonary disease; Enfermedad pulmonar obstructiva crónica; Superposición asma-Enfermedad pulmonar obstructiva crónica.