Abstract

Background: An increase in levels of C-reactive protein (CRP), a marker of systemic inflammation, is associated with reduced forced expiratory volume in 1 s (FEV₁), supporting the hypothesis that the pathophysiology of chronic obstructive pulmonary disease has a systemic inflammatory component. However, few large studies have assessed the relationship between systemic inflammation as measured by CRP and decline in lung function prospectively in a randomly selected population.

Methods: In 1991, data were collected on FEV₁ and forced vital capacity (FVC) and a blood sample was taken from 2442 randomly selected adults in a community-based cohort. In 2000 these measures were repeated in 1301 individuals. The level of serum CRP was analysed in these samples from 1991 and 2000.

Results: In cross-sectional analyses of data from 1991 and 2000, serum CRP levels were inversely related to FEV₁ and FVC. After adjustment for smoking and other confounders, the difference in FEV₁ was reduced by −9 ml (95% CI –13 to –5) and –7 ml (95% CI –13 to –2) for each mg/l increment in serum CRP in 1991 and 2000, respectively. There was no significant association between baseline serum CRP levels and decline in FEV₁ and FVC over 9 years.

Conclusions: Although serum CRP levels are inversely associated with lung function in cross-sectional studies, there was no effect of a marker of systemic inflammation on decline in lung function over 9 years.