Stages of COPD
COPD is classified into four spirometric grades (1-4) based on airflow limitation severity, and into four groups (A-D) based on symptoms and exacerbation risk, according to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines. 1
Spirometric Classification (Grades 1-4)
The spirometric classification of COPD severity is based on post-bronchodilator FEV1/FVC ratio and FEV1 percent predicted:
| Grade | Severity | Post-bronchodilator FEV1/FVC | FEV1 % predicted |
|---|---|---|---|
| 1 | Mild | <0.70 | ≥80% |
| 2 | Moderate | <0.70 | 50-79% |
| 3 | Severe | <0.70 | 30-49% |
| 4 | Very Severe | <0.70 | <30% |
Note: A post-bronchodilator FEV1/FVC ratio <0.70 confirms the presence of persistent airflow limitation. 2, 1
Symptom and Risk Assessment (Groups A-D)
Beyond spirometric classification, GOLD recommends a comprehensive assessment approach that includes:
Symptom assessment using either:
- Modified Medical Research Council (mMRC) Dyspnea Scale (≥2 indicates high symptoms)
- COPD Assessment Test (CAT) score (≥10 indicates high symptoms)
Exacerbation risk assessment:
- Low risk: 0-1 exacerbations per year without hospitalization
- High risk: ≥2 exacerbations per year or ≥1 exacerbation leading to hospitalization
This creates four patient groups:
- Group A: Low symptoms, Low risk
- Group B: High symptoms, Low risk
- Group C: Low symptoms, High risk
- Group D: High symptoms, High risk 2, 1
Modified Medical Research Council (mMRC) Dyspnea Scale
| Grade | Description |
|---|---|
| 0 | Not troubled with breathlessness except during strenuous exercise |
| 1 | Troubled by shortness of breath when hurrying or walking up a slight hill |
| 2 | Walks slower than people of the same age due to breathlessness or has to stop for breath when walking at own pace on a level surface |
| 3 | Stops for breath after walking about 100 m or after a few minutes on a level surface |
| 4 | Too breathless to leave the house or breathless when dressing or undressing |
| [2] |
Exacerbation Classification
Exacerbations are classified as:
- Mild: Treated with short-acting bronchodilators only
- Moderate: Treated with short-acting bronchodilators plus antibiotics and/or oral corticosteroids
- Severe: Patient requires hospitalization or visits the emergency room; may be associated with acute respiratory failure 2
Composite Prognostic Indices
Several multidimensional indices have been developed to better predict outcomes in COPD:
- BODE: Body mass index, airflow Obstruction, Dyspnea, Exercise capacity
- mBODE: Modified BODE (replaces 6MWD with peak oxygen consumption)
- BODEx: Exacerbations replace exercise capacity in BODE
- ADO: Age, Dyspnea, airflow Obstruction
- DOSE: Dyspnea, airflow Obstruction, Smoking status, Exacerbation frequency
- CODEx: Comorbidities, airflow Obstruction, Dyspnea, Exacerbations 2, 1
Clinical Implications and Caveats
- The GOLD classification system aims to guide treatment decisions, but studies show significant variability within each stage 3
- Group C patients (low symptoms, high risk) are relatively uncommon in clinical practice (4.2% in one study) 4
- BMI <21 kg/m² is associated with increased mortality in COPD patients 2, 1
- Comorbidities significantly contribute to disease severity and should be included in comprehensive patient evaluation 2, 1
- Early detection is crucial as most patients seek medical advice at advanced disease stages 5
The GOLD staging system provides a standardized framework for COPD assessment, but clinicians should recognize its limitations and consider the complete clinical picture when developing management plans.