Eosinophil levels predict lung function deterioration in apparently healthy individuals

BACKGROUND: While chronic respiratory diseases are among the leading causes of mortality and morbidity worldwide, little is known about the effect of blood eosinophil levels on lung function trajectories among healthy individuals. METHODS: We analyzed data of apparently healthy individuals (n=18,089) recruited for the Tel Aviv Medical Center Inflammation Survey. Blood eosinophil levels were compared between participants with normal and those with abnormal lung function. Multivariate regression was used to assess the OR of forced expiratory volume in 1 second (FEV(1)) deterioration according to baseline eosinophils in subjects with normal lung function (n=4,141) during a follow-up period of 4 years. RESULTS: Participants with an abnormal, as opposed to a normal, pulmonary function test (PFT) (n=1,832, 10.1%) had significantly higher eosinophil levels, expressed as a percentage or count (2.99%±2.00% compared to 2.67%±1.88% and 0.2210e3/µL±0.163/µL compared to 0.1810e3/µL±0.183/µL, respectively; P<0.001 for both). Among participants with a normal PFT at baseline, those with an eosinophil percentage higher than 4% showed a higher risk for FEV(1) decline above 60 mL/year (OR=1.199, 95% CI=1.005–1.431, P=0.044). CONCLUSION: Our study suggests that higher blood eosinophil levels can predict PFT deterioration even in apparently healthy subjects, implying that these individuals could benefit from frequent lung function evaluation.