Diagnostic values of peripheral blood eosinophil count, fractional exhaled nitric oxide, and total serum IgE in eosinophilic asthma

<bold>Objective:</bold> This study investigated the diagnostic value of peripheral blood eosinophil (EOS) count, fractional exhaled nitric oxide (FeNO), and serum total IgE in patients with different phenotypes of asthma. <bold>Methods:</bold> 301 patients with confirmed asthma in the Second Affiliated Hospital of Xi'an Jiaotong University were selected. Clinical data such as blood routine, induced sputum cytology, FeNO, lung function, serum total IgE, and allergen-specific IgE were collected. The diagnostic accuracy of these markers to identify eosinophilic asthma (sputum eosinophils ≥3%) was calculated using receiver operating characteristics area under the curve (ROC AUC). <bold>Results:</bold> 301 patients with confirmed asthma were enrolled in the study, including 142 patients in EA (62 males) and 159 patients in NEA group (50 males). A significant positive relationship was between percentage of sputum eosinophils and blood eosinophil count, FeNO, and serum total IgE (r=0. 605, r=0.547, r=0.359, all <italic>p</italic><0.001). ROC AUC for blood eosinophil count was 78.7% (<italic>p</italic><0.001), for FENO 79.8% (<italic>p</italic><0.001) and for serum total IgE 68.9% (<italic>p</italic><0.001) to detect eosinophilic asthma. When combining these three variables, prominent improvement was seen(AUC=88.8%, <italic>p</italic>＜0.001). <bold>Conclusions:</bold> Peripheral blood eosinophil count and FeNO can determine eosinophilic asthma as better surrogates for sputum eosinophils. Combining peripheral blood eosinophil count, FeNO, and total serum IgE shows highest diagnostic value. The combined diagnosis could promote individualized management and treatment for asthma.