Table 2.

Definition of ACO from Japanese Respiratory Society

Basic Characteristics

Post-bronchodilator FEV1/FVC < 70% in individuals 40 years of age or older

Features of COPD

(1 item out of 1–3)

1. Smoking history (> 10 pack-year) or similar air pollution exposure

2. Presence of low attenuation area showing emphysematous lesions on CT

3. Impaired pulmonary diffusion (DLCO and/or DLCO/VA <0.8)

Features of asthma

(2 items out of 1–3 or 1 item out of 1–3 and 2 items out of 4)

1. Variable (diurnal, day to day, seasonal) or paroxysmal respiratory symptoms (cough, sputum, dyspnea)

2. Asthma diagnosis history under 40 years

3. Exhaled nitric oxide > 35ppb

4-1) Complication of allergic rhinitis

2) Bronchodilator response of FEV1≥200 mL and 12% from baseline

3) Peripheral blood eosinophil count> 5% or 300 cells/μL

4) High IgE (for total or inhaled antigens)

Notes: If basic characteristics, features of asthma and features of COPD are satisfied, diagnose as ACO. Reproduced from Yanagisawa S, Ichinose M. Definition and diagnosis of asthma-COPD overlap (ACO). Allergol Int. 2018;67(2):172–178.²⁰ Copyright © 2018 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved. Creative Commons (CC BY-NC-ND 4.0; https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode).