Gender differences in the association between C-reactive protein, lung function impairment, and COPD.

Individuals with COPD have systemic inflammation that can be assessed by measuring C-reactive protein (CRP). In this paper we evaluated whether CRP is related to COPD, lung function and rate of lung function decline. We included 1237 randomly selected subjects (mean age 42, range 28-56 years) from three centers in the European Community Respiratory Health Survey: Reykjavik, Uppsala and Tartu. CRP was measured at the end of the follow-up (mean 8.3 years) and the values were divided into 4 quartiles. Fifty-three non-asthmatic subjects fulfilled spirometric criteria for COPD (FEV1/FVC < 70%). COPD occurred more often in the 4th CRP quartile (OR (95% CI) 3.21 (1.13-9.08)) after adjustment for age, gender, body weight and smoking. High CRP levels were related to lower FEV1 values in both men (-437 (-596, -279) mL) and women (-144 (-243, -44) mL). The negative association between CRP and FEV1 was significantly larger in men than women (p = 0.04). The decline in FEV1 was larger (16 (5, 27) mL) in men with high CRP levels whereas no significant association between CRP and FEV1 decline was found in women. Higher CRP values are significantly associated with COPD and lower lung function in men and women. In men higher CRP values are related to a larger decline in FEV1.