Correlation between serum biomarkers and BODE index in patients with stable COPD

Background and objective: The BODE index, based on BMI, obstructive ventilatory impairment, dyspnoea scale and exercise capacity, has been used to evaluate the severity of patients with COPD. However, the correlations between serum biomarkers and the BODE index in patients with stable COPD are not widely studied. This study evaluated potential serum biomarkers for their ability to identify smokers with COPD and reflect disease severity. Methods: A comparative study was conducted of 100 clinically stable COPD patients and 50 matched healthy smokers and the difference in levels of biomarkers between the COPD patients and healthy smokers was measured. Serum inflammatory mediators measured were growth-related oncogene-α (GRO-α), IL-8, tumour necrosis factor-α (TNF-α), matrix metalloproteinase-9 (MMP-9) and monocyte chemoattractant protein-1 (MCP-1). Variables included age, pack-years, current or ex-smoker status, inhaler or oral steroid use and BODE index components, including airflow obstruction, the distance walked in 6MWD, modified Medical Research Council (MMRC) dyspnoea scale and BMI. The association between serum biomarkers and the components of the BODE index was assessed in the COPD patients. Results: The level of serum MCP-1 was significantly different between the COPD group and the healthy smoker group (P = 0.003). Significant results in univariate and multivariate analysis of the association between biomarkers and BODE components were: serum MCP-1 correlated with FEV₁% and 6MWD; serum IL-8 and GRO-α correlated with steroid use; serum TNF-α correlated with steroid use and FEV₁%; and serum MMP-9 correlated with MMRC dyspnoea scale. Conclusions: No single specific serum inflammatory mediator was completely correlated with BODE variable parameters in patients with stable COPD. Serum MCP-1 may be an important biomarker for identifying COPD subjects from healthy smokers and classifying COPD severity.