Table. Features that, when present, favour asthma or COPD
|
Clinical feature (if measured/relevant) |
Asthma more likely |
COPD more likely |
|---|---|---|
|
Age of onset |
Before 20 | After 40 |
|
Pattern of symptoms |
Variation in respiratory symptoms:
|
Persistence of respiratory symptoms despite treatment Symptoms every day, including exertional dyspnoea History of chronic cough and sputum unrelated to specific triggers, before onset of dyspnoea |
|
Lung function |
Expiratory airflow limitation* is variable# Lung function normal between symptoms |
Expiratory airflow limitation* is persistent† Lung function abnormal between symptoms |
|
History |
Previous diagnosis of asthma Family history of asthma and allergies§ (allergic rhinitis or eczema) |
Previous diagnosis of COPD, chronic bronchitis or emphysema Heavy exposure to tobacco smoke or biomass fuels |
|
Long-term disease trajectory |
Seasonal or yearly variation in symptoms Improvements (spontaneously or in response to medication) last for weeks |
Slowly worsens over years Relief in response to medication is limited and short term |
|
Chest X-ray |
Normal | Severe hyperinflation‡ |
Features that, when present, increase the probability of either typical asthma or typical COPD. None of these features is essential to make the diagnosis of asthma or COPD, with the exception of persistent airflow limitation for making the diagnosis of COPD.
* Expiratory airflow limitation: indicated by a reduced ratio of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) on spirometry (FEV1/FVC less than the lower limit of normal (i.e. less than the 5th percentile of normal population). Typical FEV1/FVC values derived from population studies are > 0.75 in people aged 40–59 years and > 0.70 in people aged 60–80 years.
# Variable expiratory airflow limitation: variation beyond the range seen in healthy populations. It is indicated in adults by any of the following:
- a clinically important increase in FEV1 (change in FEV1 of at least 200 mL and 12% from baseline) 10–15 minutes after administration of bronchodilator
- clinically important variation in lung function (at least 20% change in FEV1) when measured repeatedly over time (e.g. spirometry on separate visits)
- a clinically important increase in lung function (at least 200 mL and 12% from baseline) after ≥ 4 weeks’ treatment trial with an ICS
- clinically important variation in peak expiratory flow (diurnal variability of more than 10%, calculated over 1–2 weeks as the average of daily amplitude per cent mean)
- a clinically important reduction in lung function (decrease in FEV1 of at least 200 mL and 12% from baseline on spirometry, or decrease in peak expiratory flow rate by at least 20%) after exercise (formal laboratory-based exercise challenge testing uses different criteria for exercise-induced bronchoconstriction)
- a clinically important reduction in lung function (15–20%, depending on the test) during a test for airway hyperresponsiveness (exercise challenge test or bronchial provocation test) measured by a respiratory function laboratory.
The greater the variations, or the more occasions excess variation is seen, the more confidently the diagnosis of variable expiratory airflow limitation consistent with asthma can be made.
† Persistent expiratory airflow limitation is indicated by reduced post-bronchodilator FEV1/FVC*
§ Lack of history of atopy does not exclude non-allergic asthma.
‡ Chest X-ray may be normal in a patient with COPD
Adapted from
Global Initiative for Asthma, Global Initiative for Obstructive Lung Disease. Diagnosis and initial treatment of asthma, COPD and asthma-COPD overlap. Updated April 2017. Global Initiative for Asthma and Global Initiative for Obstructive Lung Disease; 2017. Available from: http://ginasthma.org/gina-reports