A prospective study of systemic inflammation and decline in lung function in a general population

Abstract

Background: An increase in levels of C-Reactive Protein (CRP), a marker of systemic inflammation is associated with reduced forced expiratory volume in one second, 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 we collected data on forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) and a blood sample on 2442 randomly selected adults from a community based cohort. In 2000, we repeated these measures in 1301 individuals. The level of serum CRP, a marker of systemic inflammation was analysed in these samples from 1991 and 2000.

Results: In cross-sectional analyses of data from 1991 and 2000, serum CRP was inversely related to FEV1 and FVC. After adjustment for smoking and other confounders, the difference in FEV1 was - 9ml (95% confidence intervals CI -13 to -5) and -7ml (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 and decline in FEV1 and FVC over nine years.

Conclusions: Although serum CRP is 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 nine years.