Systemic inflammatory markers in relation to lung function in NHANES. 2007–2010

BackgroundLow-grade systemic inflammation, mainly assessed by C-reactive protein (CRP), has been associated with impaired lung function. Few studies have studied if CRP, blood eosinophils, and blood neutrophils offer additive information in relation to lung function.ObjectivesTo analyse associations between lung function and CRP, blood eosinophils, and blood neutrophils, with special regard to additive information of combining the inflammatory markers.MethodsCross-sectional study on 7753 participants, 20–80 years of age, in the National Health and Nutrition Examination Survey. Gender-based tertiles for CRP, blood eosinophils, and blood neutrophils were analysed in relation to the following lung function parameters: forced expiratory volume in 1 s (FEV1% predicted), forced vital capacity (FVC % predicted), and FEV1/FVC ratio.ResultsCRP, blood eosinophils, and blood neutrophils levels were inversely related to FEV1 and FVC. Only blood eosinophils and blood neutrophils were inversely related to FEV1/FVC ratio. Further, lower lung function was found with increased number of elevated inflammatory markers in the highest tertile (one, two or three vs. non elevated) for FEV1 (β-coeff., −2.20, −4.43, and −6.43, p < 0.001) and FVC (β-coeff., −1.70, −3.15 and −5.33, p < 0.001), respectively.Conclusions & clinical relevanceCRP, blood eosinophils, and blood neutrophils offer independent and additive information in relation to lower FEV1 and FVC in the general population. This indicates that a combination of biomarkers yields more information than the biomarkers assessed individually.