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

BACKGROUND

Low-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.

OBJECTIVES

To analyse associations between lung function and CRP, blood eosinophils, and blood neutrophils, with special regard to additive information of combining the inflammatory markers.

METHODS

Cross-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 (FEV% predicted), forced vital capacity (FVC % predicted), and FEV/FVC ratio.

RESULTS

CRP, blood eosinophils, and blood neutrophils levels were inversely related to FEV and FVC. Only blood eosinophils and blood neutrophils were inversely related to FEV/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 FEV (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 RELEVANCE: CRP, blood eosinophils, and blood neutrophils offer independent and additive information in relation to lower FEV and FVC in the general population. This indicates that a combination of biomarkers yields more information than the biomarkers assessed individually.