Th2 related biomarkers as predictors of airway eosinophilia in optimally treated smoking asthmatics: An observational study

Introduction: Smoking is associated with worse asthma outcomes and may modify airway inflammation pattern. Objective: The aim of this study is to determine the predictive value of various Th2 related biomarkers in identifying airway eosinophilia (pure and mixed) in smoking asthmatics as assessed by the measurement of cellular components in induced sputum. Methods: Nighty one patients with asthma were studied (all smokers and optimally treated). All subjects underwent sputum induction for measuring inflammatory cells, FeNO measurement, total IgE, serum periostin and blood eosinophils both as % and absolute count. Airway eosinophilia was defined as pure when >3% eosinophils and 3% eosinophils and >60% neutrophils were observed. Results: ROC analysis showed that, for the whole study population the strongest performance was that of blood eosinophils as absolute counts[cut off value 130 showed a 83% sen, 77% spec with AUC 0.86 and p Conclusion: In optimally treated smoking asthmatics measurement of blood eosinophils in absolute counts could predict airway eosinophilia. This performance was superior in the pure eosinophilic profile compared to the mixed one indicating that in optimally treated smoking asthmatics the diagnostic utility of Th2 related biomarkers depends on the underlying inflammatory profile.