Blood Eosinophil Count as a Predictor of Lung Function Decline in Healthy Individuals.

Background: Little is known about the effect of blood eosinophil count (BEC) on a decline in lung function in healthy individuals.

Objective: Using a well-established health screening database, we assessed the associations between BEC and a decline in lung function, measured as the forced expiratory volume in 1 second (FEV).

Methods: Serial BEC and FEV data were analyzed using linear mixed models adjusted for gender, height, and smoking status. The association between BEC consistency and a decline in FEV 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 a greater decline in FEV that was stronger in nonsmokers (P = 8.56 × 10) than in smokers (P = 1.52 × 10). In subpopulation analyses of 2018 individuals with consistent BECs, those with BECs consistently ≥100/μL (P = 4.58 × 10), ≥200/μL (P = 3.53 × 10), and ≥300/μL (P = 1.12 × 10) had a significantly higher dose-dependent FEV decline than those with BECs consistently <100/μL. A BEC threshold of 100/μL in nonsmokers and 200/μL in smokers may predict an accelerated decline in FEV.

Conclusions: BEC is associated with a decline in FEV, and a consistently high BEC is an independent risk factor for an accelerated decline in FEV. 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.