Asthma, COPD, and overlap syndrome
| Feature | Asthma | COPD | Asthma-COPD overlap syndrome |
|---|---|---|---|
| Age of onset | Usually childhood | Usually > 40 | Usually > 40, but may report symptoms in childhood or early adulthood |
| Symptoms | High variability over time, multiple triggers, worse at night or early morning | Continuous, worse with exertion, chronic cough, and sputum | Persistent exertional dyspnea but prominent variability |
| Background | Personal or family history of allergies or asthma | Exposure to noxious substances like tobacco | Personal or family history of allergies or asthma and personal noxious exposure |
| Disease course and response to treatment | Symptoms improve spontaneously, respond to bronchodilator and inhaled corticosteroid | Slowly progressive despite treatment, bronchodilator provides only limited relief | Symptoms are partly but significantly reduced by treatment Progression is typical and treatment needs are high |
| Chest radiography | Usually normal | Hyperinflated lungs | Hyperinflated lungs |
| Spirometry | Variable and reversible airflow limitation, may be normal between symptoms or postbronchodilator Postbronchodilator increase in FEV1 > 12% and > 200 mL from baseline Increase of 400 mL from baseline is common | Persistent airflow limitation FEV1 may be improved by therapy but postbronchodilator FEV1/FVC < 0.7 persists Postbronchodilator FEV1 ≥ 80% predicted indicates mild limitation and < 80% predicted indicates severe limitation | Airflow limitation is persistent and not fully reversible, but often with current or historic variability FEV1 may be improved by therapy but postbronchodilator FEV1/FVC < 0.7 persists Postbronchodilator FEV1 ≥ 80% predicted indicates mild and < 80% indicates severe limitation |
COPD = chronic obstructive pulmonary disease; FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity