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 (2024) categorises airway obstruction seen in spirometry into levels from mild to very severe based on the percentage of predicted FEV1.
|
GOLD Grades and Severity of Airflow Obstruction in COPD (based on post-bronchodilator FEV1) |
||
|---|---|---|
| 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 a revised classification of airway obstruction, which they use in their competency assessments.
This system has five levels and is based on Z-scores.
| Severity classification and probability of a result being found within a normal healthy population for various z-score thresholds |
||
|---|---|---|
| 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 |
Now that you know the severity grading of your patient's obstruction, you can continue their assessment.