Distribution of blood eosinophil counts in the Chinese general population

Current clinical assessments of blood eosinophil (EOS) count often overlook demographic variability, particularly in Asian populations, where large-scale data remain scarce. We aimed to define demographic-specific distributions of EOS counts and identify factors associated with elevated levels in the general Chinese population.

Using a large-scale Chinese health-check population dataset comprising over 680 000 participants (2010-2023), we conducted a cross-sectional study to characterise overall and demographic-stratified distributions of blood EOS counts and construct age- and sex-specific percentile curves. We then applied multivariable regression to quantify associations between EOS counts and selected respiratory and systemic conditions, adjusting for key demographic and clinical covariates. Robustness was evaluated through sensitivity analyses.

EOS counts showed a right-skewed distribution (median (interquartile range) 100 (60-170) cells·μL^-1) and were consistently higher in males than females (120 (80-200) versus 90 (50-140) cells·μL^-1). Age- and sex-specific percentile curves defined population-based reference ranges and demonstrated a U-shaped trajectory across age. In multivariable analyses, higher EOS counts were associated with male sex, age <20 or ≥70 years, smoking and higher body mass index. EOS counts were positively associated with major respiratory conditions, including asthma and COPD, as well as selected systemic comorbidities (all p_Bonferroni<0.05). Findings were robust in sensitivity analyses.

In this large Chinese health-check population, blood EOS counts showed substantial demographic heterogeneity. These findings support age- and sex-stratified reference ranges and may inform more context-specific thresholds for eosinophilia in clinical practice.