Narrative review of current COPD status in Japan

Abstract

Chronic obstructive pulmonary disease (COPD) causes morbidity and mortality worldwide. Due to the improvement in environmental sanitation and medical care, the general life span has increased in the past decades in Japan. However, many older patients with COPD develop a wide range of comorbidities, and the impairments in the activities of daily living result in frailty and increase social and economic burdens.Population-based studies have shown that the prevalence of COPD is approximately 10% among subjects aged ≥40 years, but more than 80% of COPD patients are underdiagnosed. The Ministry of Health, Labour, and Welfare in Japan proposed the National Health Promotion in the 21st century, termed Health Japan 21 (the second term), in 2013 to prevent the onset and progression of noncommunicable diseases (NCDs), including COPD. The government, medical society, and community have been attempting to increase the recognition of COPD and promote smoking cessation. Additionally, Japanese cohorts have revealed distinct clinical features in Japanese patients with COPD, including lower rates of patient-reported exacerbations, less frequent coexisting cardiovascular disease and metabolic syndrome, and lower use of inhaled corticosteroids in Japan compared to the Western countries. Moreover, the poor adherence to inhaled medications is found in approximately 20% of subjects, and rehabilitation is performed in 26% of hospitalized patients with COPD. Therefore, more efforts should be made to improve adherence and access to pulmonary rehabilitation. Overall, Japanese COPD patients share common clinical and social features with COPD patients in other countries. Further international corroboration may help establish better comprehensive management of the disease.

A Retrospective Claims Database Study to Clarify Disease Burden of Severe Asthma Patients with Type 2 High or Low Inflammation

“…[13][14][15][16] The higher proportion of patients with COPD in the T2-high (23.9%) and T2-low (30.1%) populations with asthma in this study compared with that in other countries where overlap occurs in approximately 20% of asthma patients 17 may be attributed to the higher age in the present study population. 18 Previous research in Japan has found that COPD is associated with higher age; 19 furthermore, our data are consistent with those reported in a previous study in Japan in which COPD was reported in 27.1% of patients with asthma. 20 In this study, the proportions of patients with asthma exacerbation were similar between the T2-high population (30.6%, 95% CI: 26.9-34.4) and T2-low population (34.6%, 95% CI: 26.6-43.3).…”

Recent Prevalence of and Factors Associated With Chronic Obstructive Pulmonary Disease in a Rapidly Aging Society: Korea National Health and Nutrition Examination Survey 2015–2019

“…31 In the most populous of those countries, the proportion of elderly people (≥ 65 years) and the prevalence of COPD ranged from 16.0% to 28.2% and 6.4% to 25.0%, respectively ( Supplementary Table 2 ). 32 33 34 South Korea, which became an aging society in 2017, is experiencing rapid aging. 35 The prevalence of COPD in Korea was similar to those in the previously mentioned countries.…”

“… 55 56 Second, the high prevalence of COPD in the elderly population may be due to the criteria for COPD used in our study. 32 33 It is well known that a fixed rate (FEV 1 /FVC < 70%) causes false-positive recognition of COPD with increasing age. 57 However, the COPD guidelines still favor using a fixed ratio regardless of age.…”

Nontuberculous mycobacterial pulmonary disease added burden to COPD and bronchiectasis in Japan

“…Nevertheless, such differences in documenting the pulmonary symptoms in claims likely apply to both cases and controls so should not affect our findings regarding the incremental burden associated with NTM-PD in Japan. Prevalence of COPD in Japan has been estimated to be approximately 10-15% in the general population and >30% among high-risk patients [41,42], but underdiagnosis is well documented [41,43,44]. In this study, COPD was identified in <5% of the JMDC population, but any potential underdiagnosis likely affected both the case and control groups comparably.…”