What is the significance of FEV1 (Forced Expiratory Volume in 1 second)/FVC (Forced Vital Capacity) ratio in Chronic Obstructive Pulmonary Disease (COPD)?

From the Guidelines

The FEV1/FVC ratio is a crucial diagnostic criterion for Chronic Obstructive Pulmonary Disease (COPD), with a reduced ratio below 0.70 indicating airflow obstruction, as stated in the 2025 GOLD Science Committee recommendations 1.

Significance of FEV1/FVC Ratio in COPD

The FEV1/FVC ratio represents the proportion of vital capacity that can be exhaled in the first second of forced expiration (FEV1) compared to the total forced vital capacity (FVC).

• A reduced FEV1/FVC ratio is the primary diagnostic criterion for COPD, indicating airflow obstruction.
• The ratio helps classify COPD severity, with lower values indicating more severe obstruction.
• As COPD progresses, this ratio typically decreases due to airway obstruction and air trapping.

Diagnostic Approach

The 2025 GOLD Science Committee recommendations suggest using pre-bronchodilator spirometry to rule out COPD and post-bronchodilator measurements to confirm the diagnosis 1.

• Post-bronchodilator FEV1/FVC ratio < 0.70 confirms the diagnosis of COPD.
• The Canadian Thoracic Society guideline also supports the use of a fixed ratio less than 0.70 to identify individuals at risk of clinically significant COPD 1.
• However, the fixed ratio approach may under- or overestimate the presence of airflow obstruction at the extremes of age.

Clinical Implications

Regular spirometry testing to monitor the FEV1/FVC ratio is recommended for COPD patients, as it provides valuable information about disease progression and response to treatment.

• The FEV1/FVC ratio is essential for diagnosing and monitoring COPD, and its reduction is associated with increased risk of exacerbations, pneumonia, and death.
• The severity of airflow obstruction in COPD should be evaluated by the magnitude of reduction in the post-bronchodilator FEV1, as stated in the 2023 Canadian Thoracic Society guideline 1.

From the FDA Drug Label

The trials enrolled patients 40 years of age or older with a clinical diagnosis of COPD, a smoking history of more than 10 pack-years, and moderate to very severe pulmonary impairment (post-bronchodilator FEV1 less than 80% predicted normal [GOLD Stage 2-4]; post-bronchodilator FEV1 to FVC ratio of less than 70%).

The FEV1/FVC ratio is significant in Chronic Obstructive Pulmonary Disease (COPD) as it is used to diagnose and assess the severity of the disease. A ratio of less than 70% indicates airflow limitation, which is a characteristic of COPD. Key points include:

• Diagnosis: The FEV1/FVC ratio is used to diagnose COPD.
• Severity assessment: The ratio helps assess the severity of COPD, with lower ratios indicating more severe disease.
• Airflow limitation: A ratio of less than 70% indicates airflow limitation, which is a hallmark of COPD 2.

From the Research

Significance of FEV1/FVC Ratio in COPD

The FEV1/FVC ratio is a crucial metric in the diagnosis and management of Chronic Obstructive Pulmonary Disease (COPD) [ 3 ]. A postbronchodilator FEV1/FVC ratio of 0.7 or less is diagnostic in a patient with dyspnea, chronic cough or sputum production, and a history of irritant exposure [ 3 ].

Diagnostic Criteria

• A postbronchodilator FEV1/FVC ratio of 0.7 or less is used to diagnose COPD [ 3 ]
• The Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages 1-4 are based on FEV1% predicted (ppFEV1) [ 4 ]
• A new severity classification scheme, STaging of Airflow obstruction by Ratio (STAR), uses FEV1/FVC ratio to categorize the severity of airflow obstruction [ 4 ]

Comparison with Other Diagnostic Criteria

• FEV1/FEV6 has been proposed as a surrogate for FVC for the diagnosis of COPD [ 5 ]
• FEV1/FEV6 shows excellent accuracy in diagnosing airflow obstruction using FEV1/FVC < 0.70 as a reference [ 5 ]
• The lower limit of normal (LLN) criterion for FEV1/FVC ratio affects the classification and outcomes of patients with COPD [ 6 ]

Clinical Implications

• The FEV1/FVC ratio is used to guide treatment decisions in COPD, including the use of long-acting beta2-agonists and long-acting muscarinic antagonists [ 3 ]
• The STAR classification system provides discrimination for mortality that is similar to the GOLD classification but with a more uniform gradation of disease severity [ 4 ]