Systemic inflammation and lung function decline in a repeated measure study on an elderly cohort

RATIONALE Decreased lung function has been linked to increased inflammation and oxidative stress. Higher C-reactive protein (CRP) levels have been associated with lower lung function in cross-sectional studies. Whether CRP, as a marker of systemic inflammation, is related with lung function decline is unresolved. METHODS We investigated the association of CRP levels on lung function decline on 2,014 lung function measurements on 803 elderly men from the Eastern Massachusetts Normative Aging Study, whose lung function (forced vital capacity [FVC] and forced expiratory volume in one second [FEV1]) was measured 2-4 times between 1995-2005. Subjects were categorized according to the median CRP level (1.61 mg/L). We used mixed linear models to estimate FVC or FEV1 decline by CRP category, adjusting for potential confounders. RESULTS FVC decline was 22.1 mL/yr (95% CI 16.7-27.4) in subjects with CRP>1.61 mg/L, while subjects with CRP<1.61 mg/L had a FVC decline of 13.0 mL/yr (95% CI 7.9-18.1). The effect of CRP on FVC decline was highly significant (p=0.004). FEV1 decline was 17.0 mL/yr (95% CI 13.1-21.0) in subjects with CRP>1.61 mg/L, while those with CRP>1.61 mg/L had a FEV1 decline of 11.3 mL/yr (95% CI 7.5-15.0). The effect of CRP on FEV decline was also was significant (p=0.01). CONCLUSIONS Our results indicate that higher CRP levels are associated with a decline in lung function in the elderly.