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

Am J Respir Crit Care Med. 2006 Sep 15;174(6):626-32. doi: 10.1164/rccm.200602-243OC. Epub 2006 Jun 15.


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 (CRP) were determined in 1,131 subjects without known pulmonary disease.

Measurements and main results: Ninety-six of the study participants (8.5%) had FEV(1) of less than 80% of predicted values. There was a strong inverse association between CRP levels and quartiles of FEV(1). The median CRP levels in nonsmoking participants were 2.5, 1.8, 1.7, and 1.3 mg/L in the first, second, third, and forth FEV(1) quartiles, respectively (p < 0.0001). A similar inverse association was present in smoking subjects (median CRP levels were 3.8, 2.3, 2.0, and 1.9 mg/L in the first, second, third, and fourth FEV(1) 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 CRP 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.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Biomarkers / blood
  • Body Mass Index
  • C-Reactive Protein / metabolism*
  • Confidence Intervals
  • Cross-Sectional Studies
  • Exercise / physiology
  • Female
  • Forced Expiratory Flow Rates / physiology*
  • Humans
  • Male
  • Metabolic Syndrome / blood
  • Metabolic Syndrome / physiopathology
  • Middle Aged
  • Prognosis
  • Reference Values
  • Risk Factors
  • Smoking / blood
  • Smoking / physiopathology
  • Vital Capacity / physiology*


  • Biomarkers
  • C-Reactive Protein