Table 1.

Obstructive lung disease (FEV₁/FVC<0.7): definition of subtypes

OLD subtype	Criterion
COPD	Physician’s diagnosis of COPD (chronic bronchitis or emphysema) OR chest radiograph or CT: diagnosis of emphysema OR airflow obstruction with <20% improvement of FEV1 with bronchodilator and no alternative explanation for the patient’s respiratory symptoms
Asthma	Physician’s diagnosis of asthma AND ≥20% improvement of FEV1 with bronchodilator
Bronchiectasis	Diagnosis of bronchiectasis by a pulmonologist based on clinical and radiologic data OR chest radiograph or CT: diagnosis of bronchiectasis according to radiologist
Obstructive bronchiolar disorders	Diagnosis of bronchiolitis obliterans (or obliterative/constrictive bronchiolitis) by pulmonologist OR CT diagnosis of bronchiolitis obliterans (or obliterative/constrictive bronchiolitis) by radiologist
ILD associated airflow obstruction	Physician’s diagnosis of ILD PLUS CT/chest radiograph consistent with ILD and/or 1 of the following criteria TLC≤80% of predicted Bronchoscopic or surgical lung biopsy results consistent with ILD

OLD=obstructive lung disease; FEV₁=forced expiratory volume; FVC=forced vital capacity; COPD = chronic obstructive pulmonary disease; CT= computed tomography; ILD=intersitial lung disease; TLC=total lung capacity