High eosinophil counts predict decline in FEV₁: results from the CanCOLD study

Area of Science:

• Respiratory Medicine
• Immunology
• Pulmonology

Background:

• Blood eosinophil levels are increasingly recognized as potential biomarkers in respiratory diseases.
• Understanding the association between eosinophils and lung function decline is crucial for managing chronic respiratory conditions.

Purpose of the Study:

• To investigate the relationship between peripheral blood eosinophil counts and the rate of lung function decline in adults over 40 years of age.
• To determine if higher eosinophil levels are associated with accelerated loss of forced expiratory volume in 1 second (FEV₁).

Main Methods:

• Analysis of blood eosinophil counts in 1120 participants from the Canadian Cohort of Obstructive Lung Disease (CanCOLD) study.
• Longitudinal assessment of lung function (FEV₁) using spirometry over 18-month intervals.
• Statistical modeling (random mixed-effects regression) to assess the association between eosinophil levels and FEV₁ decline, adjusting for confounders.

Main Results:

• Participants with eosinophil counts ≥300 cells·µL⁻¹ experienced a significantly greater decline in FEV₁ compared to those with lower counts.
• The rate of FEV₁ decline was -67.30 mL/year for the high eosinophil group (≥300 cells·µL⁻¹), versus -32.99 mL/year for the lowest group (<150 cells·µL⁻¹).
• In Chronic Obstructive Pulmonary Disease (COPD) patients, higher eosinophil counts correlated with structural airway abnormalities detected via CT imaging.

Conclusions:

• A peripheral blood eosinophil count of ≥300 cells·µL⁻¹ is an independent risk factor for accelerated lung function decline in older adults.
• Elevated eosinophil levels may indicate the presence of undetected structural abnormalities in the airways.