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      Clinical Characteristics and Outcomes of Patients with Asthma–COPD Overlap in Japanese Patients with COPD

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          Asthma–COPD overlap (ACO) has been reported as an association with a lower quality of life, frequent exacerbations, and higher mortality than those with COPD alone. However, clinical characteristics and outcomes of ACO remain controversial.

          Patients and Methods

          We conducted a prospective observational study analyzing data of patients with stable COPD enrolled from the Ishinomaki COPD Network Registry. Patients with features of asthma who had a history of respiratory symptoms that vary over time and intensity, together with documented variable expiratory airflow limitation, were identified, and then defined as having ACO. The characteristics, frequency of exacerbations, and mortality during the 3-year follow-up were compared between patients with ACO and patients with COPD alone.


          Among 387 patients with COPD, 41 (10.6%) were identified as having ACO. Patients with ACO tended to be younger, have higher BMI, have a shorter smoking history, and use more respiratory medications, especially inhaled corticosteroids. Inflammatory biomarkers including fractional exhaled nitric oxide, blood eosinophil count, total immunoglobulin E (IgE) level, and presence of antigen-specific IgE were significantly higher in patients with ACO than in those with COPD alone. Lung function, mMRC score, CAT score, and comorbidity index were not different between the groups. The annual rate of all exacerbations and severe exacerbations required hospital admission were not different between ACO and COPD alone (0.20 vs 0.14, 0.12 vs 0.10, events per person, respectively). Mortality was significantly higher in patients with COPD alone compared with those with ACO during the study period (P=0.037).


          The results of our study indicate that ACO is not associated with poor clinical features nor outcomes in an outpatient COPD cohort receiving appropriate treatment.

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          Most cited references 34

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          A new method of classifying prognostic comorbidity in longitudinal studies: Development and validation

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            Investigation of the freely available easy-to-use software ‘EZR' for medical statistics

             Y Kanda (2012)
            Although there are many commercially available statistical software packages, only a few implement a competing risk analysis or a proportional hazards regression model with time-dependent covariates, which are necessary in studies on hematopoietic SCT. In addition, most packages are not clinician friendly, as they require that commands be written based on statistical languages. This report describes the statistical software ‘EZR' (Easy R), which is based on R and R commander. EZR enables the application of statistical functions that are frequently used in clinical studies, such as survival analyses, including competing risk analyses and the use of time-dependent covariates, receiver operating characteristics analyses, meta-analyses, sample size calculation and so on, by point-and-click access. EZR is freely available on our website ( and runs on both Windows (Microsoft Corporation, USA) and Mac OS X (Apple, USA). This report provides instructions for the installation and operation of EZR.
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              Standardisation of spirometry.


                Author and article information

                Int J Chron Obstruct Pulmon Dis
                Int J Chron Obstruct Pulmon Dis
                International Journal of Chronic Obstructive Pulmonary Disease
                12 November 2020
                : 15
                : 2923-2929
                [1 ]Department of Respiratory Medicine, Japanese Red Cross Ishinomaki Hospital , Ishinomaki, Miyagi, Japan
                [2 ]Department of Pulmonary Medicine, Sendai Kosei Hospital , Sendai, Miyagi, Japan
                Author notes
                Correspondence: Seiichi KobayashiDepartment of Respiratory Medicine, Japanese Red Cross Ishinomaki Hospital , 71 Nishimichishita, Hebita, Ishinomaki986-8522, JapanTel +81 225 21 7220Fax +81 225 96 0122 Email
                © 2020 Kobayashi et al.

                This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms (

                Page count
                Figures: 0, Tables: 9, References: 36, Pages: 7
                Original Research

                Respiratory medicine

                asthma, asthma–copd overlap, copd, exacerbations, mortality


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