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

Inga Sif Ólafsdóttir¹, Thórarinn Gíslason², Bjarni Thjóðleifsson³, Ísleifur Ólafsson⁴, Davíd Gíslason², Rain Jõgi⁵, Christer Janson¹

¹Department of Medical Sciences: Respiratory Medicine and Allergology, Uppsala University, Uppsala, Sweden; ²Department of Allergy, Respiratory Medicine and Sleep, Landspitali University Hospital, Reykjavik, Iceland; ³Department of Gastroenterology, Landspitali University Hospital, Reykjavik, Iceland; ⁴Department of Clinical Biochemistry, Landspitali University Hospital, Reykjavik, Iceland; ⁵Lung Clinic of Tartu University Hospital, Tartu, Estonia

Abstract: 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.

Keywords: C-reactive protein, COPD, body mass index, spirometry, ECRHS