Clinical characteristics and ten-year trend of peripheral blood eosinophilia among health screening program recipients at a tertiary hospital of South Korea

Background: Eosinophilia in specific conditions such as allergic diseases, helminthic infection, and drug-induced reaction is well recognized. In the present study, we evaluated the clinical characteristics of eosinophilia and change in prevalence over 10 years in recipients of health screening program at a tertiary hospital of South Korea.

Methods: We collected the data of health screening program recipients at the health promotion center of Chung-Ang University Hospital from 2004 to 2013. Eosinophilia was defined when the absolute eosinophil count exceeds 500/µL in the peripheral blood. We reviewed health-related questionnaires and laboratory findings of health screening program which might be related to eosinophilia.

Results: The cumulative prevalence of eosinophilia was 4.0% (1,963 out of 48,858). Most of eosinophilia cases (96.6%) were in mild degree (500 to 1500/µL). Eosinophilic subjects were older and more male-predominant (P<0.001, respectively). Subjects with eosinophilia showed lower level of FEV1%, FVC% and FEV1/FVC than those without eosinophilia (P<0.001, respectively). Of note, annual prevalence was in decreasing trend from 2004 to 2013 (OR=0.942, 95% CI: 0.926-0.958, P<0.001). Eosinophilic subjects showed higher positive rate for common parasite ELISA (P<0.001). The positive rate for ELISA to parasites increased with advancing age in subjects with eosinophilia (P=0.002).

Conclusions: Eosinophilia in general, healthy population was not uncommon and usually in mild degree. The prevalence of eosinophilia decreased from 2004 to 2013, which might be related to decrease in parasitic infection in young Korean population.