Blood eosinophil count in the general population: typical values and potential confounders

Area of Science:

• Immunology
• Pulmonology
• Epidemiology

Background:

• Growing interest in blood eosinophil counts for managing asthma and COPD.
• Typical blood eosinophil levels and confounder impacts are not well-defined in the general population.

Purpose of the Study:

• Define typical blood eosinophil levels in the general population.
• Identify factors associated with elevated blood eosinophil counts.
• Estimate blood eosinophil counts in a healthy sub-population.

Main Methods:

• Random sample of 11,042 Austrian general population subjects.
• Identified factors associated with high blood eosinophil counts (>75th percentile).
• Excluded subjects with identified factors to estimate "healthy" median blood eosinophil counts.

Main Results:

• Factors associated with high eosinophils: age ≤18 years, asthma, smoking, positive skin prick test, COPD, metabolic syndrome, male sex, obesity.
• These factors showed an additive effect on blood eosinophil counts.
• In healthy adults (>18 years), median eosinophil counts were higher in males (120 cells·µL⁻¹) than females (100 cells·µL⁻¹) and did not change with age.

Conclusions:

• Median blood eosinophil counts in adults are lower than commonly considered normal.
• Blood eosinophil counts are significantly influenced by multiple factors with additive effects.
• Findings aid in interpreting blood eosinophil levels in clinical practice for respiratory conditions.