Asthma and COPD Overlap Syndrome (ACOS): Risk Factors and Contributing Factors

Background:The exact description of asthma and chronic obstructive pulmonary disease overlap syndrome (ACOS) is uncertain. This study aims to determine the frequency and symptoms of ACOS and to verify certain risk factors associated with ACOS. Methods:Severe asthmatic patients with and without ACOS above 40 years old participated in this cross-sectional study. The receiver operating curve analysis (ROC) was used to assess the best cutoff values of age, body mass index (BMI), and spirometric data to distinguish asthma patients with overlap syndrome from asthma patients without overlap syndrome. Univariable and multivariable binary logistic regression was used to determine demographic and clinical factors that were associated with ACOS and asthma. Results:Of the 88 patients, 46 (52.2%) had ACOS and 42 (47.7%) had just severe asthma. The mean age of ACOS patients (Sd) was 54.91(12.57) years and in asthma-only patients was 48.69 (13.51). The ROC analysis for age and BMI showed that age ⩾ 49 years and BMI ⩾ 27 kg/m(2)were the best predictors of ACOS in this study. Spirometry data showed that the forced vital capacity (FVC) (lit) > 2.16, forced expiratory volume in the first second (FEV1) > 69, FEV1 / FVC > 96.5, and FVC (%) > 63 cut points could be used to determine the diagnostic criteria between ACOS and asthma only, respectively. Multivariate modeling showed that among the demographic and clinical variables, only age over 49 years (odds ratio [OR], 3.53 [95% CI, 1.07-11.63]p= 0.025) and living in a big city (OR, 7.42 [95% CI, 1.75-31.49]p= 0.007) were significant. Conclusion:Age over 49 and BMI above 27 have a significant association with ACOS. Also, living in a big city is considered to be another risk factor for ACOS compared with asthma. Spirometry can help distinguish ACOS from severe asthma in this study.