Table 1.

Features favoring asthma or COPD for syndromic diagnosis of airway disease based on the Global Initiative for Asthma/Global Initiative for Chronic Obstructive Lung Disease report

Feature	Asthma	COPD
Age of onset	Before age 20 years	After age 40 years
Pattern of respiratory symptoms	Variation in symptoms over time Symptoms worsen during the night or early morning Symptoms triggered by exercise, emotional change (including laughter), or exposure to dust/allergens	Persistence of symptoms despite treatment Good and bad days but always daily respiratory symptoms and exertional dyspnea Chronic cough and sputum preceded by onset of dyspnea, unrelated to triggers
Lung function	Record of variable airflow limitation (spirometry, peak flow)	Record of persistent airflow limitation (post-bronchodilator FEV1/FVC <0.7)
Lung function between symptoms	Normal	Abnormal
Past history or family history	Previous doctor diagnosis of asthma Family history of asthma and other allergic conditions (allergic rhinitis, dermatitis)	Previous doctor diagnosis of COPD, chronic bronchitis, or emphysema Heavy exposure to a risk factor: tobacco smoke and biomass fuels
Time course	No worsening of symptoms over time. Symptoms vary either seasonally or from year to year May improve spontaneously or have a response to bronchodilator immediately or to ICS over weeks	Symptoms slowly worsen over time (progressive course over years) Rapid-acting bronchodilator treatment provides only limited symptom relief
Chest X-ray	Normal	Severe hyperinflation

Notes: Adapted with permission from Global Initiative for Asthma and Global Initiative for Chronic Obstructive Lung Disease. Diagnosis of diseases of chronic airflow limitation: asthma, COPD, and asthma-COPD overlap syndrome (ACOS).¹

Abbreviations: FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; ICS, inhaled corticosteroid.