Identification of Asthma-COPD Overlap, Asthma, and Chronic Obstructive Pulmonary Disease Phenotypes in Patients with Airway Obstruction: Influence on Treatment Approach

Abstract

Background: Many studies have described asthma-COPD overlap (ACO) among patients diagnosed with asthma or chronic obstructive pulmonary disease (COPD), but less so in broad populations of patients with chronic airway obstruction. Objective: This study aimed to (i) examine the prevalence of ACO, asthma, and COPD phenotypes among subjects referred for pulmonary function testing (PFT), who had airway obstruction in spirometry (forced expiratory volume in 1 s [FEV₁]/forced vital capacity [FVC] <0.7); and (ii) delineate the therapeutic approach of each group. Methods: Cross-sectional study of patients who were referred for PFT at the Rokach Institute, in Jerusalem. Working definitions were as follows: (a) COPD: post-bronchodilator (BD) FEV₁/FVC <0.70; (b) asthma: physician-diagnosed asthma before age 40 and/or minimum post-BD increase in FEV₁ or FVC of 12% and 200 mL; and (c) ACO: the combination of the 2. Demographics, smoking habits, episodes of exacerbation, health-related quality of life (HRQL), and respiratory medication utilization were analyzed. Results: Of 3,669 referrals from January 1 to April 30, 2017, 1,220 had airway obstruction of which 215 were included. Of these, 82 (38.1%) had ACO, 49 (22.8%) asthma, and 84 (39.1%) COPD. ACO subjects tended to (a) be predominantly female; (b) be older than asthmatics, (c) be smokers; (d) have worse HRQL in the activity domain; and (d) have more exacerbations. Treatment of ACO and COPD patients differed from that of asthmatics, but not from each other, in the proportion of subjects on maintenance treatment, use of LABA, LAMA, and ICS, alone or in combination, and in the number of inhaler devices used by patients. Conclusion: ACO represented >1/3 of patients referred for PFT. Despite a clearly identifiable phenotype, ACO patients received treatment similar to COPD patients, suggesting poor ACO identification. Our data emphasize the need to raise the awareness of ACO among clinicians, in order to guide better recognition and appropriate treatment in individual patients.