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. 2021 May 11;11(5):859. doi: 10.3390/diagnostics11050859

Table 2.

Diagnostic criteria for ACO issued by the Japanese Respiratory Society [110].

Fundamental Aspects: Over 40 Years of Age, Chronic Airway Obstruction Defined By < 70% of Post-Bronchodilator FEV1/FVC
[Features of COPD]
At least one positive features of the followings (1, 2, 3)		 (Features of asthma)
Two positive features of the following 1, 2, 3 items; or at least one positive features of 1, 2, 3 plus two positive features of 4

  1. Smoking history > 10 pack-years or equivalent exposure to air pollution

  1. Variable in diurnal, daily or seasonal symptoms, or paroxysmal respiratory symptoms (cough, sputum, dyspnea)
  • 2.

    Low attenuation area indicating emphysematous changes on HRCT
  • 2.

    Past history of asthma before the age of 40 years
  • 3.

    Attenuated diffusion capacity (%DLCO < 80% or %DLCO/VA < 80%)
  • 3.

    FeNO > 35 ppb
4-1 Comorbidity of perennial allergic rhinitis
4-2 Reversibility of airway obstruction (FEV1 > 12% and > 200 mL)
4-3 Blood eosinophil > 5% or > 300 cells/μL
4-4 Elevated serum IgE (total IgE or specific IgE for perennial inhaled allergens)

COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in one second; FeNO, fractional exhaled nitric oxide; FVC, forced vital capacity; IgE, immunoglobulin E; DLCO, diffusing capacity of the lung carbon monoxide; VA, alveolar volume.