Inverse association between pulmonary function and C-reactive protein in apparently healthy subjects

Rationale: Increased levels of systemic markers of inflammation have been reported in patients with impaired lung function due to obstructive or restrictive lung disease. Objective: We tested the hypothesis that a decline in lung function within the normal range may be associated with a systemic subclinical inflammation. Methods: Pulmonary function tests, cardiorespiratory fitness, components of the metabolic syndrome, and high-sensitivity C-reactive protein (CIRP) were determined in 1,131 subjects without known pulmonary disease. Measurements and Main Results: Ninety-six of the study participants (8.5%) had FEV1 of less than 80% of predicted values. There was a strong inverse association between CRIP levels and cluartiles of FEV1. The median CIRP levels in nonsmoking participants were 2.5, 1.8, 1.7, and 1.3 mg/L in the first, second, third, and forth FEV1 quartiles, respectively (p < 0.0001). A similar inverse association was present in smoking subjects (median CIRP levels were 3.8, 2.3, 2.0, and 1.9 mg/L in the first, second, third, and fourth FEV, quartiles, respectively; p < 0.0001). These associations remained highly significant after adjustment for age, sex, components of the metabolic syndrome, and fitness level (p = 0.0005). Conclusions: An inverse linear relationship exists between CIRP concentrations and measures of pulmonary function in subjects without pulmonary disease and in never-smokers. These results indicate that systemic inflammation may be linked to early perturbations of pulmonary function.