Having diagnosed your patient, the next step is to classify and document the severity of your patient’s airflow obstruction. This will help guide your treatment decisions.
Grades and severity of airway obstruction - GOLD
GOLD (2026) and NICE guidelines categorize airway obstruction seen in spirometry into levels which range from mild to very severe, based on the percentage of predicted FEV1.
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GOLD Grades and Severity of Airflow Obstruction in COPD (based on post-bronchodilator FEV1) |
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|---|---|---|
| GOLD 1: | Mild | FEV1 ≥ 80% predicted |
| GOLD 2: | Moderate | 50% ≤ FEV1 < 80% predicted |
| GOLD 3: | Severe | 30% ≤ FEV1 < 50% predicted |
| GOLD 4: | Very severe | FEV1 < 30% predicted |
© 2023, 2024, Global Initiative for Chronic Obstructive Lung Disease, available from www.goldcopd.org, published in Deer Park, IL, USA.
Grades and severity of airway obstruction - ARTP
The Association for Respiratory Technology and Physiology (ARTP) recommends different, more updated way of classifying airway obstruction, which is used within their competency assessments.
This approach uses Z-scores and describes airflow obstruction across five levels.
Using Z-scores helps avoids the bias that can occur when using percentage predicted values, particularly in very young or older people
| Severity classification and probability of a result being found within a normal healthy population for various z-score thresholds |
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|---|---|---|
| Threshold for Z-score | Severity grading | Approximate chance of finding this result in a healthy population |
| < - 1.645 | Mild | 1 in 20 |
| < - 2.00 | Moderate | 1 in 40 |
| < - 2.50 | Moderately Severe | 1 in 150 |
| < - 3.00 | Severe | 1 in 750 |
| < - 3.50 | Very Severe | 1 in 30,000 |
Whichever scale you use, remember: the severity of airflow obstruction does not always correlate to the impact the COPD is having on the patient and their life.
There is a lot of evidence to suggest that the severity of obstruction is not necessarily reflected in the patient’s symptoms. For example, a patient with grade 3 (severe) obstruction may be less affected by their symptoms than a person at grade 1 (mild).
This is because COPD is a heterogenous disease which means that every patient experiences symptoms, such as breathlessness differently.
GOLD recommends using a holistic approach to understand the impact that your patient’s symptoms are having on their everyday life and what their risk of exacerbations is likely to be .
Find out how to do this here.