Evaluation of BODE index and its relationship with systemic inflammation mediated by proinflammatory biomarkers in patients with COPD

INTRODUCTION BODE index, a multidimensional grading system which is based on Body mass index, airway Obstruction, Dyspnea scale, and Exercise capacity, has been increasingly used for the evaluation of chronic obstructive pulmonary disease (COPD). Many of the systemic manifestations of COPD are shown to be mediated by elevated levels of proinflammatory biomarkers. OBJECTIVE We aimed to investigate the relationship between the BODE index, its components, disease severity, and proinflammatory biomarkers like C-reactive protein (CRP), tumor necrosis factor (TNF)-α, and interleukin (IL)-6. MATERIALS AND METHODS A cross-sectional study which included 290 clinically stable COPD patients and 80 smoker controls was conducted. Medical history, body mass index, pulmonary function tests, 6-minute walking test, and modified scale of Medical Research Council dyspnea scale were evaluated. BODE scores were determined. Systemic inflammation was evaluated with the measurement of CRP, TNF-α, and IL-6 in the serum samples of all studied subjects. The correlation between inflammatory biomarkers and BODE index was assessed in COPD patients. RESULTS We found a significant relationship between COPD stages and BODE index. Our analysis showed significant association between systemic biomarkers and components of the BODE index. Both TNF-α and CRP levels exhibited weak but significant correlation with BODE index. Serum IL-6 concentrations exhibited significant correlation with 6-minute walking test, modified scale of Medical Research Council, and BODE index (r=0.201, P=0.004; r=0.068, P=0.001; and r=0.530, P=0.001, respectively). Also, an inverse and significant correlation was observed between BODE index and FEV1 (r=0.567, P=0.001). IL-6 exhibited a highly significant and inverse correlation with FEV1 (r=-0.580, P=0.001). CONCLUSION BODE index should be considered for evaluating patients with COPD. Also, IL-6 seems to be a potential biomarker that may enable determination of the severity and prediction of the course of the disease.