Diagnostic accuracy of sputum outcomes in chronic stable asthma

Background Asthma with non‐remitting airflow obstruction may not always be differentiated from COPD with airway hyperreactivity. Many attempts have been made to find useful markers for the distinction between these two disorders. Objective and methods In order to help the finding of a useful marker for the diagnosis of asthma in the population of patients with airway obstruction we analysed the diagnostic accuracy of sputum eosinophils and sputum ECP in 91 patients with asthma, 15 patients with chronic bronchitis, 32 patients with chronic obstructive pulmonary disease (COPD) and 20 controls subjects, by performing ROC analysis. Results Sputum eosinophils were above the normal range of our laboratory (0–3.7%) in 48 asthma patients and in six COPD patients, while sputum ECP (normal range