Blood eosinophil count as a predictor of lung function decline in healthy individuals.

Lee, So-Hee; Ahn, Kyung-Min; Lee, Suh-Young; Kim, Sun-Sin; Park, Heung-Woo

BACKGROUND Little is known about the effect of blood eosinophil count (BEC) on lung function decline in healthy individuals. OBJECTIVE Using a well-established health screening database, we assessed the associations between BEC and decline in lung function, measured as the forced expiratory volume in 1 s (FEV1). METHODS Serial BEC and FEV1 data were analyzed using linear mixed models adjusted for gender, height, and smoking status. The association between BEC consistency and FEV1 decline was evaluated in subpopulation analyses. RESULTS A total of 4634 individuals were enrolled. The mean number of health-screenings was 7.49 over an average of 11.74 years of observation. A higher log2-transformed BEC was significantly associated with greater FEV1 decline that was stronger in non-smokers (P = 8.56x10-8) than in smokers (P = 1.52x10-3). In subpopulation analyses of 2018 individuals with consistent BECs, those with BECs consistently ≥ 100/μL (P = 4.58x10-6), ≥ 200/μL (P = 3.53x10-7), and ≥ 300/μL (P = 1.12x10-3) had a significantly higher, dose-dependent FEV1 decline than those with BECs consistently < 100/μL. A BEC threshold of 100/μL in non-smokers and 200/μL in smokers may predict accelerated FEV1 decline. CONCLUSIONS BEC is associated with a decline in FEV1, and a consistently high BEC is an independent risk factor for accelerated FEV1 decline. These results suggest the use of the BEC to identify healthy individuals at high risk for developing chronic lung disease, which in turn may enable a tailored preventive strategy.