FEV₁/FVC Severity Stages for Chronic Obstructive Pulmonary Disease

Area of Science:

• Pulmonary Medicine
• Respiratory Disease Research
• Clinical Trial Analysis

Background:

• Chronic obstructive pulmonary disease (COPD) diagnosis relies on FEV1/FVC ratio, yet severity is graded by FEV1% predicted (ppFEV1).
• Existing ppFEV1-based staging may not fully capture airflow obstruction severity or patient outcomes.

Purpose of the Study:

• To evaluate a novel COPD severity classification system, STaging of Airflow obstruction by Ratio (STAR), utilizing the FEV1/FVC ratio.
• To compare the STAR classification's performance against the established Global Initiative for Chronic Obstructive Lung Disease (GOLD) staging.

Main Methods:

• The STAR classification, based on FEV1/FVC thresholds (0.60-0.70, 0.50-0.60, 0.40-0.50, <0.40 for stages 1-4), was tested in the COPDGene cohort (N=10,132).
• Replication analysis was performed using the Pittsburgh SCCOR and Emphysema COPD Research Registry (N=2,017).
• Agreement between GOLD and STAR staging was assessed using weighted Bangdiwala B values.

Main Results:

• High agreement was observed between GOLD and STAR staging (B=0.89 in COPDGene, B=0.88 in Pittsburgh).
• STAR significantly discriminated between no obstruction and Stage 1 for mortality, quality of life, dyspnea, airway wall thickness, exacerbations, and lung function decline.
• STAR identified more patients with Stage 3/4 disease eligible for lung transplantation and lung volume reduction surgery evaluations.

Conclusions:

• The STAR classification demonstrates comparable mortality discrimination to GOLD staging but with a more uniform disease severity gradation.
• STAR offers superior differentiation of patient symptoms, disease burden, and prognosis compared to ppFEV1-based GOLD staging.
• The STAR system shows reduced sensitivity to race/ethnicity and demographic variations, suggesting broader applicability.