Biomarkers for differentiation of patients with asthma and chronic obstructive pulmonary disease.

Objective: Asthma and chronic obstructive pulmonary disease (COPD) are airflow limitation diseases with similar clinical manifestations but different pathophysiologic mechanisms. To implement the appropriate treatment, it is important to distinguish between asthma and COPD which sometimes might result difficult in clinical practice. We evaluated biomarkers to distinguish between asthma and COPD. Methods: Blood eosinophil counts and fractional exhaled nitric oxide (FeNO) levels were analyzed. Serum periostin, interleukin-25 (IL-25), and immunoglobulin E (IgE) concentrations were compared between patients with asthma (n = 60), including atopic-asthma (n = 30) and non-atopic asthma (n = 30), and patients with COPD (n = 30). Results: Significantly higher peripheral blood eosinophil counts (p < 0.001), FeNO levels (p < 0.001), and total serum IgE (P = 0.003) concentrations, but not serum periostin (p = 0.584) or serum IL-25 (p = 0.085) concentrations, were detected in patients with asthma compared to patients with COPD. Serum periostin and IgE concentrations were increased in patients with atopic-asthma compared with those with non-atopic asthma and COPD (p < 0.05). The FeNO levels were significantly correlated with the peripheral blood eosinophil counts (r = 0.430, p = 0.001) and serum IL-25 concentrations (r = 0.338, p = 0.009) in patients with asthma. The serum periostin concentrations were also correlated with the serum IgE concentrations (r = 0.375, p = 0.003) and FeNO levels (r = 0.291, p = 0.024) in patients with asthma. Asthma patients were effectively differentiated from COPD patients based on the FeNO levels (p < 0.001) and peripheral blood eosinophil counts (p < 0.001). Conclusions: FeNO levels and peripheral blood eosinophil counts were useful biomarkers for distinguishing between patients with asthma and COPD. Serum periostin and IgE concentrations could be biomarkers for atopic asthma.