Research Article Clinical and Functional Characteristics of Subjects with Asthma, COPD, and Asthma-COPD Overlap: A Multicentre Study in Vietnam Sy Duong-Quy , 1,2 Huong Tran Van, 3 Anh Vo Thi Kim, 4 Quyen Pham Huy, 5 and Timothy J. Craig 2 1 Bio-Medical Research Center, Lam Dong Medical College, Dalat, Vietnam 2 Division of Pulmonary, Allergy and Critical Care Medicine, Penn State College of Medicine, Hershey, PA, USA 3 Department of Health Science, ang Long University, Hanoi, Vietnam 4 Nam Anh General Hospital, Binh Duong Province, Vietnam 5 Department of Clinical Immuno-Allergology, Hai Phong University, Haiphong, Vietnam Correspondence should be addressed to Sy Duong-Quy; sduongquy.jfvp@gmail.com Received 25 November 2017; Revised 17 February 2018; Accepted 22 February 2018; Published 1 April 2018 Academic Editor: Isabella Annesi-Maesano Copyright©2018SyDuong-Quyetal.isisanopenaccessarticledistributedundertheCreativeCommonsAttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Introduction. Subjects with asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) share common features of patients with asthma and COPD. Our study was planned to describe the clinical and functional features of subjects with ACO compared to asthma and COPD patients. Subjects and Methods. Study subjects who met the inclusion criteria were classified into three different groups: asthma, COPD, and ACO groups. All study subjects underwent clinical examination and biological and functional testing. ey were then followed for 6 months to evaluate the response to conventional treatment. Results. From March 2015 to March 2017, 76 asthmatic (mean age: 41 ± 22 years), 74 COPD (59 ± 13 years), and 59 ACO (52 ± 14 years) subjects were included. e percentage of subjects with dyspnea on excretion in the ACO group was higher than that in asthma and COPD groups (P < 0.001 and P < 0.05, resp.). Subjects with COPD and ACO had significant airflow limitation (FEV 1 ) compared to asthma (64 ± 17% and 54 ± 14% versus 80 ± 22%; P < 0.01 and P < 0.01, resp.). e levels of FENO in subjects with asthma and ACO were significantly higher than those in subjects with COPD (46 ± 28 ppb and 34 ± 12 ppb versus 15 ± 8ppb; P < 0.001 and P < 0.001, resp.). VO 2 max and 6MWD were improved in study subjects after 6 months of treatment. Increased CANO and AHI > 15/hour had a significant probability of risk for ACO (OR � 33.2, P < 0.001, and OR � 3.4, P < 0.05, resp.). Conclusion. Subjects with ACO share the common clinical and functional characteristics of asthma and COPD but are more likely to have sleep apnea. e majority of patients with ACO have a favourable response to combined treatment. 1. Introduction e prevalence of asthma and chronic obstructive pulmo- nary disease (COPD) increased worldwide during the last decades and is expected to continue to rise in the next few decades. Asthma and COPD are a major problem for public health in many countries, especially for those with low- income status [1–3]. Recently, research has stressed that some patients might have clinical features of both asthma and COPD (asthma-COPD overlap syndrome or ACOS), particularly adult smokers with high reversibility of airflow obstruction and bronchial or systemic eosinophilic in- flammation [4, 5]. It has been suggested that ACOS includes subjects with several different forms of airway diseases (phenotypes) caused by different underlying mechanisms (endotypes). us, ACOS has been somewhat defined as the coexistence of the features of two different diseases (asthma and COPD) in the same individual [6, 7]. Currently, to avoid the misunderstanding that ACOS is a single disease (syndrome), the term “ACO” (asthma- COPD overlap) has been recommended in a joint GINA and GOLD document [2]. In this document, ACO has been Hindawi Canadian Respiratory Journal Volume 2018, Article ID 1732946, 11 pages https://doi.org/10.1155/2018/1732946