Objective: To identify and characterize asthma with blood eosinophilia in adults. Methods: This cross-sectional study consisted of 164 asthma patients, aged 18 years or older. Multivariate analyses by logistic regression were performed to identify clinical characteristics and biomarkers associated with asthma with blood eosinophilia (defined as asthma and a peripheral blood eosinophil count ≥400 cells/mm3). To evaluate the diagnostic accuracy of these biomarkers, the sensitivity, specificity and predictive values were calculated. Additionally, the area under the receiver operating characteristic (ROC) curve (AUC) was estimated for each biomarker. Results: Overall, 37.8% (95%CI: 30.7-45.4%) of asthma patients had blood eosinophilia. The following factors were associated with this characteristic: patient age <50 years (OR 3.25; 95% CI: 1.33-7.94), a serum level of IgE ≥300 UI/mL (OR 2.32; 95%CI: 1.14-4.75), and an Asthma Control Test (ACT) score <20 points (OR 3.10; 95%CI: 1.35-4.75); asthma with blood eosinophilia was also associated with a baseline FEV1/FVC <70% (OR 2.68; 95%CI: 1.28-5.59). On the other hand, age <50 years and ACT score <20 showed the highest sensitivity (above 80% each). Serum IgE level ≥300 UI/mL had the highest specificity (almost 68%). Finally, those with an ACT score <20 had the highest AUC (68%). Conclusions: In our study population, one-third of asthmatic adults had asthma with blood eosinophilia. Furthermore, the prevalence was greater in those ≤50 years of age; these patients experienced more severe, more poorly controlled asthma and had higher total serum IgE levels.
Keywords: Asthma; adult; biomarker; eosinophils; immunoglobulin E; phenotype.