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      Understanding low COPD exacerbation rates in Japan: a review and comparison with other countries

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          COPD is associated with significant morbidity and is one of the leading causes of death worldwide. Periods of exacerbation, the acute worsening of symptoms, are interspersed throughout the disease’s natural history and can result in increased treatment burden and hospitalization for patients with COPD. The frequency of exacerbations varies between countries, with both epidemiological studies and randomized controlled trials (RCTs) showing significant differences in observed prevalence rates. Differences in study design and the healthcare setting are likely to contribute to differences in exacerbation frequency, however the perceived rate of exacerbations in Japan is currently lower then the rest of the world. This review identified nine cohort studies and five RCTs that reported COPD annual exacerbation rates in Japan in the ranges of 0.1–2.1 and 0.33–1.79, respectively. The difference in exacerbation rate between studies appeared greater than the difference between Japan and Western countries, likely because of disparities between settings, design, and inclusion criteria. Of these, only one (Understanding the Long-Term Impacts of Tiotropium) had uniform inclusion criteria across different regions. This study found that the annual rate of exacerbation events per patient in Japan was 0.61, compared with 0.85 worldwide in the placebo groups. This review summarizes the published rates of COPD exacerbations in Japan and the rest of the world and explores the hypotheses as to why rates in Japan might be lower than other countries. These include access to medical care, variance in the associated morbidity profile, environmental factors, diagnostic crossover with related diseases, and differences in study design (including the underreporting of COPD exacerbations in Japan). Understanding the reasons why COPD exacerbation rates appear lower in Japan could help clinicians to recognize and modify treatment behaviors, which may lead to improved patient outcomes in all populations.

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          Most cited references 28

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          The clinical features of the overlap between COPD and asthma

          Background The coexistence of COPD and asthma is widely recognized but has not been well described. This study characterizes clinical features, spirometry, and chest CT scans of smoking subjects with both COPD and asthma. Methods We performed a cross-sectional study comparing subjects with COPD and asthma to subjects with COPD alone in the COPDGene Study. Results 119 (13%) of 915 subjects with COPD reported a history of physician-diagnosed asthma. These subjects were younger (61.3 vs 64.7 years old, p = 0.0001) with lower lifetime smoking intensity (43.7 vs 55.1 pack years, p = 0.0001). More African-Americans reported a history of asthma (33.6% vs 15.6%, p < 0.0001). Subjects with COPD and asthma demonstrated worse disease-related quality of life, were more likely to have had a severe COPD exacerbation in the past year, and were more likely to experience frequent exacerbations (OR 3.55 [2.19, 5.75], p < 0.0001). Subjects with COPD and asthma demonstrated greater gas-trapping on chest CT. There were no differences in spirometry or CT measurements of emphysema or airway wall thickness. Conclusion Subjects with COPD and asthma represent a relevant clinical population, with worse health-related quality of life. They experience more frequent and severe respiratory exacerbations despite younger age and reduced lifetime smoking history. Trial registration NCT00608764
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            Annual change in pulmonary function and clinical phenotype in chronic obstructive pulmonary disease.

            Although the rate of annual decline in FEV1 is one of the most important outcome measures in chronic obstructive pulmonary disease (COPD), little is known about intersubject variability based on clinical phenotypes. To examine the intersubject variability in a 5-year observational cohort study, particularly focusing on emphysema severity. A total of 279 eligible patients with COPD (stages I-IV: 26, 45, 24, and 5%) participated. We conducted a detailed assessment of pulmonary function and computed tomography (CT) at baseline, and performed spirometry every 6 months before and after inhalation of bronchodilator. Smoking status, exacerbation, and pharmacotherapy were carefully monitored. Emphysema severity was evaluated by CT and annual measurements of carbon monoxide transfer coefficient. Using mixed effects model analysis, the annual decline in post-bronchodilator FEV1 was -32±24 (SD) ml/yr (n=261). We classified the subjects of less than the 25th percentile as Rapid decliners, the 25th to 75th percentile as Slow decliners, and greater than the 75th percentile as Sustainers (-63±2, -31±1, and -2±1 [SE] ml/yr). Emphysema severity, but not %FEV1, showed significant differences among the three groups. Multiple logistic regression analysis demonstrated that the Rapid decliners were independently associated with emphysema severity assessed either by CT or carbon monoxide transfer coefficient. The Sustainers displayed less emphysema and higher levels of circulating eosinophils. Emphysema severity is independently associated with a rapid annual decline in FEV1 in COPD. Sustainers and Rapid decliners warrant specific attention in clinical practice.
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              Predictors of mortality in hospitalized adults with acute exacerbation of chronic obstructive pulmonary disease.

              There is a need to identify clinically meaningful predictors of mortality following hospitalized COPD exacerbation. The aim of this study was to systematically review the literature to identify clinically important factors that predict mortality after hospitalization for acute exacerbation of chronic obstructive pulmonary disease (COPD). Eligible studies considered adults admitted to hospital with COPD exacerbation. Two authors independently abstracted data. Odds ratios were then calculated by comparing the prevalence of each predictor in survivors versus nonsurvivors. For continuous variables, mean differences were pooled by the inverse of their variance, using a random effects model. There were 37 studies included (189,772 study subjects) with risk of death ranging from 3.6% for studies considering short-term mortality, 31.0% for long-term mortality (up to 2 yr after hospitalization), and 29.0% for studies that considered solely intensive care unit (ICU)-admitted study subjects. Twelve prognostic factors (age, male sex, low body mass index, cardiac failure, chronic renal failure, confusion, long-term oxygen therapy, lower limb edema, Global Initiative for Chronic Lung Disease criteria stage 4, cor pulmonale, acidemia, and elevated plasma troponin level) were significantly associated with increased short-term mortality. Nine prognostic factors (age, low body mass index, cardiac failure, diabetes mellitus, ischemic heart disease, malignancy, FEV1, long-term oxygen therapy, and PaO2 on admission) were significantly associated with long-term mortality. Three factors (age, low Glasgow Coma Scale score, and pH) were significantly associated with increased risk of mortality in ICU-admitted study subjects. Different factors correlate with mortality from COPD exacerbation in the short term, long term, and after ICU admission. These parameters may be useful to develop tools for prediction of outcome in clinical practice.

                Author and article information

                Int J Chron Obstruct Pulmon Dis
                Int J Chron Obstruct Pulmon Dis
                International Journal of COPD
                International Journal of Chronic Obstructive Pulmonary Disease
                Dove Medical Press
                26 October 2018
                : 13
                : 3459-3471
                [1 ]Respiratory Medical Affairs, Development and Medical Affairs, GSK K.K., Tokyo, Japan
                [2 ]Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
                [3 ]Department of Respiratory Medicine, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
                [4 ]Respiratory Franchise (omit Medical), GlaxoSmithKline, Brentford, Middlesex, UK, paul.8.jones@
                [5 ]Institute of Infection and Immunity, St George’s, University of London, London, UK, paul.8.jones@
                Author notes
                Correspondence: Paul Jones, Respiratory Franchise (omit Medical), GlaxoSmithKline, GSK House, 980 Great West Road, Brentford, Middlesex TW8 8GS, London, UK, Email paul.8.jones@

                These authors contributed equally to this work

                © 2018 Ishii 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.


                Respiratory medicine

                copd, exacerbation rate, asthma-copd overlap, japan


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