The asthma and chronic obstructive pulmonary disease overlap syndrome in tertiary care setting Thailand

ABSTRACT

BACKGROUND: Asthma and chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) is an increasingly recognized clinical entity. ACOS significantly impacts on patient outcome compared to isolated asthma or COPD. However, ACOS definition and diagnosis criteria have not been well standardized. ACOS prevalence and clinical features in Thailand has never been studied. Objective: To investigate the prevalence and clinical features of ACOS compared to isolated asthma or COPD among patients with clinician-diagnosis of obstructive airway diseases. OBJECTIVE: To investigate the prevalence and clinical features of ACOS compared to isolated asthma or COPD among patients with clinician-diagnosis of obstructive airway diseases. METHODS: Spirometry, skin prick test (SPT) and allergens specific IgE (sIgE) were done. Serum total IgE, exhaled nitric oxide (FeNO) and blood eosinophils were measured. High resolution computed tomography (HRCT) was performed. Smoking history, pollution, biomass exposure and symptoms (Asthma Control Test [ACT], COPD assessment test [CAT], Modified Medical Research Council Dyspnea Scale [MMCR]) were assessed. Patients were classified to isolated asthma, COPD or ACOS according to predefined definitions for this study. RESULTS: A total 92 patients were enrolled 58 patients with clinician-diagnosed of late onset asthma and 34 with clinician-diagnosed COPD. The mean age was 67.4 years. Thirty-four asthma patients (58.6%) were considered to have ACOS with postbronchodilator forced expiratory volume in 1 second (FEV₁)/forced vital capacity ratio <0.7 and/or presence of emphysema on HRCT. In addition, 10 COPD patients (28.6%) were classified as ACOS if they had bronchodilator reversibility (FEV₁ ≥ 12% and ≥ 200 mL) and positive SPT or sIgE. Hence, total of 44 from 92 patients (47.8%) with obstructive airway diseases were found to have ACOS, while isolated asthma and COPD were found in 24 patients equally. No difference in symptoms assessed by CAT, ACT, or MMRC was found between 3 groups of patients. Neither serum total IgE nor blood eosinophils counts distinguished ACOS from asthma and COPD (p = 0.83 and p = 0.40). FeNO was higher in pure COPD than ACOS and asthma (p = 0.03). CONCLUSION: ACOS is prevalent in late-onset asthma or clinician-diagnosed COPD who were treated in tertiary care clinic. However, we found no difference in symptoms, blood eosinophils or serum total IgE between groups.