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      COPD uncovered: a cross-sectional study to assess the socioeconomic burden of COPD in Japan

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          COPD remains a major health problem in Japan. Patients with COPD experience a reduced quality of life (QoL) and have a higher chance of work impairment and productivity loss. However, there is a lack of data on the impact of COPD in terms of QoL and work activity impairment in Japan. This study assessed the socioeconomic burden of COPD in Japan and the impact it may have on the working age population.

          Patients and methods

          This was a 2-year retrospective chart review in COPD patients aged ≥40 years, with at least one health care visit to clinic or hospital in the previous 12 months. Patients were required to have available medical charts for at least the previous 24 months. Symptoms were assessed using COPD assessment test score; EuroQoL Group 5 Dimension (EQ-5D-5L) and work productivity and activity impairment general health questionnaires were used to evaluate health-related QoL and work productivity, and health care resource utilization data were obtained from clinical charts.


          In total, 71 patients aged <65 years, and 151 patients aged ≥65 years were included; the majority of patients had moderate or severe airflow limitation. Exacerbations (moderate or severe) were reported by ~35% of patients in both age groups; 52.1% and 62.9% of patients in the <65-year and ≥65-year age groups had COPD assessment test scores ≥10. EQ-5D-5L index scores in the <65-year and ≥65-year age groups were 0.79 and 0.77, respectively. Work productivity and activity impairment scores were higher in <65-year age group. Annual costs of health care resource use per patient in the <65-year and ≥65-year age groups were ¥438,975 (US$4,389) and ¥467,871 (US$4,678), respectively. Costs due to productivity loss were estimated to be ¥5,287,024 (US$52,870) in the <65-year age group and ¥3,018,974 (US$30,187) in the ≥65-year age group.


          COPD represents a significant socioeconomic burden in Japan. Patients with COPD report significant use of health care resources. Higher impact on work impairment and productivity loss was observed frequently in the working age population.

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          Most cited references 25

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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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            Characterisation of phenotypes based on severity of emphysema in chronic obstructive pulmonary disease.

            Airflow limitation in chronic obstructive pulmonary disease (COPD) is caused by a mixture of small airway disease and emphysema, the relative contributions of which may vary among patients. Phenotypes of COPD classified purely based on severity of emphysema are not well defined and may be different from the classic phenotypes of "pink puffers" and "blue bloaters". To characterise clinical phenotypes based on severity of emphysema, 274 subjects with COPD were recruited, excluding those with physician-diagnosed bronchial asthma. For all subjects a detailed interview of disease history and symptoms, quality of life (QOL) measurement, blood sampling, pulmonary function tests before and after inhalation of salbutamol (0.4 mg) and high-resolution CT scanning were performed. Severity of emphysema visually evaluated varied widely even among subjects with the same stage of disease. No significant differences were noted among three groups of subjects classified by severity of emphysema in age, smoking history, chronic bronchitis symptoms, blood eosinophil count, serum IgE level or bronchodilator response. However, subjects with severe emphysema had significantly lower body mass index (BMI) and poorer QOL scores, evaluated using St George's Respiratory Questionnaire (SGRQ), than those with no/mild emphysema (mean (SD) BMI 21.2 (0.5) vs 23.5 (0.3) kg/m(2), respectively; SGRQ total score 40 (3) vs 28 (2), respectively; p<0.001 for both). These characteristics held true even if subjects with the same degree of airflow limitation were chosen. The severity of emphysema varies widely even in patients with the same stage of COPD, and chronic bronchitis symptoms are equally distributed irrespective of emphysema severity. Patients with the phenotype in which emphysema predominates have lower BMI and poorer health-related QOL.
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              Use of a preference-based measure of health (EQ-5D) in COPD and asthma.

              EQ-5D is a generic preference-based measure of health that can help to understand the impact of asthma and chronic obstructive pulmonary disease (COPD). The purpose of this paper was to synthesize literature on the validity and reliability of EQ-5D use in studies of asthma and COPD, and estimate EQ-5D utility scores associated with stage of disease. A structured search was conducted in EMBASE and MEDLINE (1988-2007) using keywords relevant to respiratory disease and EQ-5D. Original research studies in asthma or COPD that reported EQ-5D results and/or psychometric properties were included. Studies that reported psychometric properties supported the construct validity, test-retest reliability, and responsiveness of EQ-5D in asthma (seven studies) and COPD (nine studies), although some evidence of ceiling effects were observed in asthma studies. In asthma studies that reported summary scores (n=11), EQ-5D index-based scores ranged from 0.42 (SD 0.30) to 0.93 (SD not reported). In COPD studies (n=8), scores ranged from 0.52 (SD 0.16) to 0.84 (SD 0.15). While few asthma studies reported scores by severity level, sufficient studies in COPD were available to calculate pooled mean utility scores according to GOLD stage: stage I=0.74 (0.62-0.87), stage II=0.74 (0.66-0.83), stage III=0.69 (0.60-0.78) and stage IV=0.61 (0.44-0.77) (most severe). Evidence generally supported the validity and reliability of EQ-5D in asthma and COPD. Utility scores associated with COPD stage may be useful for modeling health outcomes in economic evaluations of treatments for COPD.

                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
                28 August 2018
                : 13
                : 2629-2641
                [1 ]Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan, atarui1@
                [2 ]Department of Respiratory Medicine, Graduate School of Medicine, Juntendo University, Tokyo, Japan
                [3 ]Department of Respiratory Medicine, Graduate School of Medicine, Osaka City University, Osaka, Japan
                [4 ]Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
                [5 ]Research Institute for Respiratory Diseases, Shin-Yurigaoka General Hospital, Kawasaki City, Japan
                [6 ]Department of Pulmonary Medicine, Faculty School of Medicine, Hokkaido University, Hokkaido, Japan
                [7 ]Medical Division, Novartis Pharma K.K., Tokyo, Japan
                [8 ]Market Access Division, Novartis Pharma K.K., Tokyo, Japan
                [9 ]Market Access Division, Novartis Pharma AG, Basel, Switzerland
                Author notes
                Correspondence: Ataru Igarashi, Department of Drug Policy and Management, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan, Tel +81 3 5841 4828, Email atarui1@
                © 2018 Igarashi 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.

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