Correlation among the levels of C-reactive protein and interleukin-18, quality of life, and lung function in patients with chronic obstructive pulmonary disease

Abstract

To determine the correlation among the levels of C-reactive protein (CRP) and interleukin-18 (IL-18), quality of life, and pulmonary function in patients with chronic obstructive pulmonary disease (COPD),and to evaluate George's respiratory questionnaire (SGRQ). From October 2008 to March 2009, 39 patients with an acute exacerbation COPD (the AECOPD group), 21 patients with stable COPD (the COPD group), and 22 normal people (the control group) were enrolled in our study. The serum CRP level was measured with Beckman Coulter Immage and the IL-18 level was measured by ELISA. All subjects completed the SGRQ assessment and all patients with COPD accepted pulmonary function test. The serum levels of CRP and IL-18, and SGRQ scores in the AECOPD group were significant1y higher than those in the COPD group and the control group (P<0.01). The serum levels of CRP and IL-18 and SGRQ scores in the COPD group were significant1y higher than those in the control group (P<0.01). The serum levels of CRP and IL-18 in the AECOPD group and the COPD group were negatively correlated with FEV1% and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC). SGRQ scores in the AECOPD group and the COPD group were negatively correlated with FEV1% and FEV1/FVC. The serum levels of CRP, IL-18 in the AECOPD group and the COPD group were positively correlated with SGRQ scores. CRP and IL-18 are involved in the process of inflammatory reaction of COPD, which could be markers of the acute exacerbation period of COPD. The serum levels of CRP and IL-18 might be related to the lung dysfunction and the lower quality of life in the patients with COPD. SGRQ is an effective, susceptible, and feasible method to evaluate the quality of life in patients with COPD.