Chronic obstructive pulmonary disease (COPD)

Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria[1]Global Initiative for Chronic Obstructive Lung Disease (GOLD). Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: 2024 report. 2024 [internet publication]. https://goldcopd.org/2024-gold-report

Classification of severity of airflow limitation in COPD:

In pulmonary function testing, a post-bronchodilator FEV₁/FVC ratio of <0.7 is commonly considered diagnostic for COPD. The Global Initiative for Chronic Obstructive Lung Disease (GOLD) system categorises airflow limitation into stages. In patients with FEV₁/FVC <0.7:

• 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.

The GOLD guideline uses a combined 'ABE' approach to assess patients according to their level of symptoms and previous history of exacerbations. Symptoms are assessed using the Modified British Medical Research Council (mMRC) or COPD assessment test (CAT) scale. These can be found in the GOLD guidelines. GOLD cautions against the use of the mMRC dyspnoea scale alone for assessing patients, as symptoms of COPD go beyond dyspnoea alone. For this reason, the CAT is preferred. However, GOLD acknowledges that the use of the mMRC scale is widespread, and so a threshold of an mMRC grade ≥2 is still included to define 'more breathless' patients, as opposed to 'less breathless' patients, in its assessment criteria. Exacerbations are assessed independently of symptoms to highlight their clinical relevance.

• Group A: low risk (0-1 exacerbations per year, not requiring hospitalisation) and fewer symptoms (mMRC 0-1 or CAT <10)

• Group B: low risk (0-1 exacerbations per year, not requiring hospitalisation) and more symptoms (mMRC ≥2 or CAT ≥10)

• Group E: high risk (≥2 exacerbations per year, or ≥1 requiring hospitalisation) and any level of symptoms.