Supplementary Material for: Blood eosinophil count and its determinants in a Chinese population-based cohort

Introduction: Blood eosinophil count has been shown markedly variable across different populations. However, its distribution in Chinese general population remains unclear. We aimed to investigate blood eosinophil count and its determinants in a Chinese general population.

Methods: In this population-based study, general citizens of Sichuan province in China were extracted from the China Pulmonary Health study. Data on demographics, personal and family history, living condition, lifestyle, spirometry and complete blood count test were obtained and analyzed. A stepwise multivariate binary logistic regression analysis was performed to identify determinants of high blood eosinophils (>75th percentile).

Results: A total of 3310 participants were included, with a mean age (SD) of 47.0 (15.6) years. In total population, the median blood eosinophil count was 110.0 (IQR 67.2-192.9) cells/μL, lower than that in smokers (133.4 cells/μL, IQR 79.3-228.4) and patients with asthma (140.7 cells/μL, IQR 79.6-218.2) or post-bronchodilator airflow limitation (141.5 cells/μL, IQR 82.6-230.1), with a right-skewed distribution. Multivariate analyses revealed that oldness (aged ≥60 years) (OR 1.66, 95% CI 1.11-2.48), smoking ≥ 20 pack-years (OR 1.90, 95% CI 1.20-3.00), raising dog/cat (OR 1.72, 95% CI 1.17-2.52) and occupational exposure to dust, allergen and harmful gas (OR 1.58, 95% CI 1.15-2.15) were significantly associated with high blood eosinophils.

Conclusion: This study identifies a median blood eosinophil count of 110.0 cells/μL and determinants of high blood eosinophils in a Chinese general population, including oldness (aged ≥60 years), smoking ≥ 20 pack-years, raising dog/cat and occupational exposure to dust, allergen and harmful gas.