Functional and radiological characteristics of asthma combined chronic obstructive pulmonary disease overlap

Background Persons with asthma–chronic obstructive pulmonary disease (COPD) overlap (ACO) are a crucial but poorly characterized group. In spite of the numbers of patients with ACO have increased, there is minimal confirmed evidence regarding diagnostic features and choices of treatment. So, the aim of this study was to identify the physiological and radiological characteristics of patients with ACO. Patients and methods This study was performed on 200 patients classified into 38 patients diagnosed as having asthma, 132 patients diagnosed as having COPD, and 30 patients diagnosed as having ACO, who were chosen based on clinical features. All patients underwent pulmonary function tests, and multislice computed tomography imaging. Results The mean age of our study population was 61 years. The mean age in COPD group was higher compared with asthma and ACO groups (63.9±7.8 vs. 44.84±12.2 and 56.7±8, respectively), with a predominance of males in COPD and females in asthma, with a higher smoking index in patients with COPD than those with ACO and asthma (47.05±37.7, 13.53±2.2, and 2.47±1.46, respectively). Measurements of forced expiratory volume in 1 s (FEV1) by liters before bronchodilator therapy is greater in patients with asthma than ACO and COPD groups (1.89±0.42, 1.52±0.39, and 1.35±0.4, respectively), with highly significant difference (P<0.001). With airway reversibility, it is also greater in patients with asthma than ACO and COPD groups (2.85±0.49, 1.99±0.47, and 1.41±0.39, respectively), with a highly significant difference (P<0.001). Airway internal diameter of patients with COPD is greater than ACO and asthma groups (4.03±0.3, 3.92±0.17, and 2.82±0.31, respectively), with a highly significant difference (P<0.001). On the contrary, airway external diameter of patients with COPD is greater than asthma and ACO groups, with a highly significant difference (P<0.001). Airway wall thickness of patients with asthma is greater than ACO and COPD groups, with a highly statistical difference (P<0.001). There is no relation between thickness of airway wall and airway obstruction, expressed as FEV1 %predicted, in patients with asthma and COPD. This study results confirmed the correlation between the thickness of airway wall and airway obstruction, expressed as FEV1 %predicted, in patients with ACO. Conclusion Bronchial wall thickness measured by chest high resolution computed tomography (HRCT) is increased in patients with asthma than those with ACO and COPD, with a high statistical significance.