COPD Staging Framework
The current standard for COPD staging uses a dual-system approach: spirometric grading (GOLD 1-4) based on FEV1 percent predicted combined with the ABCD assessment tool that incorporates symptom burden and exacerbation history to guide treatment decisions. 1
Spirometric Classification (GOLD Grades 1-4)
The spirometric severity is determined by post-bronchodilator FEV1/FVC ratio <0.70 to confirm obstruction, followed by FEV1 percent predicted grading: 1, 2
- GOLD 1 (Mild): FEV1 ≥80% predicted 2
- GOLD 2 (Moderate): FEV1 50-79% predicted 2
- GOLD 3 (Severe): FEV1 30-49% predicted 2
- GOLD 4 (Very Severe): FEV1 <30% predicted 2
Critical caveat: The fixed ratio of 0.70 may overdiagnose COPD in patients >60 years and underdiagnose in younger patients <50 years. 1 Some guidelines recommend using the lower limit of normal (LLN) in these age groups to improve diagnostic specificity. 2
For patients with initial FEV1/FVC ratios between 0.6-0.8, repeat spirometry is recommended to account for day-to-day variability and increase diagnostic specificity. 1
ABCD Assessment Tool (Treatment-Guiding Classification)
The major paradigm shift since 2017 is that spirometric staging (GOLD 1-4) no longer determines treatment intensity—only the ABCD classification does. 1 This system uses two axes:
Symptom Assessment:
- mMRC ≥2 or CAT ≥10 indicates high symptom burden (groups B or D) 2
- mMRC <2 or CAT <10 indicates low symptom burden (groups A or C) 2
Exacerbation Risk Assessment:
- High risk: ≥2 moderate exacerbations OR ≥1 hospitalization in past year (groups C or D) 2
- Low risk: 0-1 moderate exacerbation without hospitalization (groups A or B) 2
Resulting Groups:
- Group A: Low symptoms, low exacerbation risk 1
- Group B: High symptoms, low exacerbation risk 1
- Group C: Low symptoms, high exacerbation risk 1
- Group D: High symptoms, high exacerbation risk 1
Prognostic Performance Considerations
Important clinical nuance: Group B patients (high symptoms, preserved lung function) have surprisingly worse mortality than Group C patients (low symptoms, worse lung function), with 5-8 times higher cardiovascular and cancer mortality. 3 This counterintuitive finding means Group B patients warrant aggressive cardiovascular and malignancy screening despite better spirometry. 3
The ABCD system predicts exacerbations better than spirometry alone (annual exacerbation rates: A=0.35, B=0.45, C=0.58, D=0.74), but spirometric staging remains superior for predicting mortality and lung function decline. 4
Multidimensional Staging (Optional Enhanced Assessment)
For patients with GOLD 2-4 disease, the BODE index provides superior prognostic information by incorporating: 2, 5
- Body mass index
- Obstruction (FEV1% predicted)
- Dyspnea (mMRC scale)
- Exercise capacity (6-minute walk distance)
The BODEx index substitutes exacerbation history for exercise capacity and is recommended for GOLD 1-2 patients. 2
Phenotype Recognition
Several guidelines recognize specific phenotypes that modify treatment: 2
- Chronic bronchitic: Productive cough ≥3 months for ≥2 consecutive years 2
- Emphysematous: Absence of productive cough with radiographic emphysema 2
- Frequent exacerbator: ≥2 exacerbations annually 2
- Asthma-COPD overlap syndrome (ACOS) 2
Practical Staging Algorithm
- Confirm diagnosis: Post-bronchodilator FEV1/FVC <0.70 (or <LLN if age <50 or >70 years) 1, 2
- Grade obstruction severity: Assign GOLD 1-4 based on FEV1% predicted 2
- Assess symptoms: Use mMRC and/or CAT scores 2
- Determine exacerbation risk: Count moderate/severe exacerbations and hospitalizations in past year 2
- Assign ABCD group: This determines pharmacologic treatment intensity 1
- Consider BODE/BODEx: For GOLD 2-4 patients requiring enhanced prognostication 2
- Identify phenotype: To guide specific therapeutic interventions 2
The spirometric grade (GOLD 1-4) is retained for research, epidemiology, and describing disease severity, but treatment decisions are made exclusively using the ABCD classification. 1