Elevated plasma fibrinogen associated with reduced pulmonary function and increased risk of chronic obstructive pulmonary disease

We tested whether increased concentrations of the acute-phase reactant fibrinogen correlate with pulmonary function and rate of chronic obstructive pulmonary disease (COPD) hospitalization. We measured plasma fibrinogen and forced expiratory volume in 1 s (FEV₁), and assessed prospectively COPD hospitalizations in 8,955 adults from the Danish general population. Smokers with plasma fibrinogen in the upper and middle tertile (> 3.3 and 2.7-3.3 g/L) had 7% (95% confidence interval [CI]: 5-8%) and 2% (0-3%) lower percentage predicted FEV₁ than smokers with fibrinogen in the lower tertile (< 2.7 g/L). The equivalent decreases in nonsmokers were 6% (4-7%) and 0% (-1-2%), respectively. Individuals with plasma fibrinogen in the upper and middle tertile had COPD hospitalization rates of 93 and 60 compared with 52 per 10,000 person-years in individuals with fibrinogen in the lower tertile (log-rank: p < 0.001 and p = 0.31). After adjusting for age, body mass index, sex, pack-years, and recent respiratory infections, relative risks for COPD hospitalization were 1.7 (95% Ch 1.1-2.6) and 1.4 (0.9-2.1) in individuals with fibrinogen in the upper and middle versus lower tertile. In conclusion, elevated plasma fibrinogen was associated with reduced FEV₁ and increased risk of COPD. This could not be explained by smoking alone.