What is the COPD (Chronic Obstructive Pulmonary Disease) Gold classification?

COPD GOLD Classification System

The GOLD classification system for COPD consists of two components: spirometric grades (1-4) based on airflow limitation severity and symptom/exacerbation risk assessment groups (A-D) that guide treatment decisions. 1, 2

Spirometric Classification (Grades 1-4)

The spirometric classification is based on post-bronchodilator FEV1/FVC ratio <0.70 (confirming airflow limitation) and FEV1 percent predicted:

Grade	Severity	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%

Symptom and Risk Assessment (Groups A-D)

Since the 2017 GOLD update, the ABCD assessment tool is based exclusively on:

1. Symptom burden (using either mMRC or CAT scores)
2. Exacerbation history

This represents a significant change from previous versions where spirometric grades were used to determine ABCD grouping 1.

Symptom Assessment Tools:

• mMRC Dyspnea Scale: Threshold ≥2 indicates high symptoms
• CAT Score: Threshold ≥10 indicates high symptoms

Exacerbation Risk Assessment:

• Low risk: 0-1 exacerbation per year (not leading to hospitalization)
• High risk: ≥2 exacerbations per year OR ≥1 exacerbation leading to hospitalization

Resulting Groups:

• Group A: Low symptoms, Low risk (mMRC 0-1 OR CAT <10; AND 0-1 exacerbation with no hospitalization)
• Group B: High symptoms, Low risk (mMRC ≥2 OR CAT ≥10; AND 0-1 exacerbation with no hospitalization)
• Group C: Low symptoms, High risk (mMRC 0-1 OR CAT <10; AND ≥2 exacerbations OR ≥1 with hospitalization)
• Group D: High symptoms, High risk (mMRC ≥2 OR CAT ≥10; AND ≥2 exacerbations OR ≥1 with hospitalization)

Clinical Implications

The choice of symptom assessment tool can affect group assignment. Studies show only moderate agreement (κ=0.77) between mMRC and CAT/SGRQ for categorizing patients 3.

Research demonstrates that the 2017 GOLD classification system results in:

1. Significant redistribution of patients compared to earlier versions, with approximately half of patients previously classified as Group D now reclassified to Group B 4
2. Group B becoming more heterogeneous with higher exacerbation risk than in previous classifications 4

The separation of spirometric assessment from symptom/exacerbation grouping acknowledges that FEV1 alone is not a good predictor of exacerbation risk 5. However, studies show that lung function impairment (including inspiratory capacity and DLCO) still parallels disease severity and should be considered in comprehensive patient assessment 6.

Treatment Implications

Treatment recommendations are now based on the ABCD groups rather than spirometric grades:

• Group A: Short-acting bronchodilator as needed
• Group B: Long-acting bronchodilator (escalate to dual bronchodilators for persistent symptoms)
• Group C: LAMA preferred (consider LABA+ICS if persistent exacerbations)
• Group D: LAMA+LABA combination (consider triple therapy for persistent exacerbations) 1, 2

Pitfalls and Caveats

1. The fixed FEV1/FVC ratio of 0.70 may lead to overdiagnosis in older patients (>60 years) 1
2. Group C (low symptoms, high risk) represents a relatively small proportion of patients in real-world populations 3
3. Within Group D, exacerbation rates vary significantly depending on whether risk classification is based on lung function, exacerbation history, or both 3
4. The GOLD classification, while useful for guiding initial therapy, may not fully capture the heterogeneity of COPD and should be complemented by assessment of comorbidities and phenotypes 6

Regular reassessment of symptoms, exacerbations, and lung function is essential for monitoring disease progression and adjusting treatment accordingly.