Gao J, et al. - The aim of this study was to investigate sputum cell counts in patients with asthma–COPD overlap (ACO) which are different from those in patients with asthma and COPD as well as to explore the association between sputum cell counts in bronchial reversibility and bronchial hyperresponsiveness (BHR). Researchers reported that sputum cell counts as an inflammatory biomarker could carry some information to distinguish ACO, asthma and COPD, and these biomarkers require more investigations to provide diagnostic value in the differentiation between ACO, asthma and COPD.

Methods

• For this purpose, three hundred seventy-four patients took an interest in the examination, involving 142 patients with asthma, 160 patients with COPD and 72 patients with ACO.
• All patients experienced the following tests on the same day: pulmonary function test (PFT), BHR test or bronchodilator reversibility test and inducing sputum.
• Based on a clinical history, PFT values and BHR test or bronchodilator reversibility test, they were classified into the asthma group, COPD group or ACO group.

Results

• It was observed in the findings that the three groups had different PFT values (p<0.001) except for forced vital capacity (FVC) between the asthma and ACO groups (p=0.378).
• Results revealed that the sputum levels of eosinophil% were diminished in patients with COPD when compared with those in patients with asthma and ACO (p<0.001 and p<0.001, respectively).
• A difference was found in sputum neutrophil% and macrophage% counts among the 3 groups (p<0.001 and p<0.001, respectively).
• However, there was no difference in sputum eosinophil% counts between patients with ACO and asthma (p=0.668) as well as no difference was found in the percentage of induced sputum cells between the stage of airway obstruction and the stage of BHR.