Abstract
Objective
The prevalence rates of bronchial asthma (BA) and chronic obstructive pulmonary disease (COPD) are 3-11% and 8-16%, respectively, in the general Japanese adult population. Few reports on patients' perceptions of BA, cough variant asthma (CVA), COPD, and asthma and COPD overlap (ACO) are available in Japan, and we aimed to investigate the agreement between the perception and diagnosis of BA and COPD-related diseases.
Methods
The subjects were 229 datasets matched to the sex and age distribution of the Japanese population of 1,000 adult patients who underwent respiratory function tests and screening for each disease at Nagasaki University Hospital between July 2014 and July 2017. The patients' self-perceptions of diagnosed BA, CVA, COPD, emphysema, chronic bronchitis, and ACO were determined.
Results
In total, 229 datasets were included in this study. The prevalence of BA was 10.0% (23 cases, including 2 CVA and 6 ACO cases) and 11.8% (27 cases, including 6 ACO cases). The prevalence of ACO was 2.6% (28.6% of BA and 22.2% of COPD), and that of CVA was 0.9% (8.7% of BA). The perception of COPD-related diseases had a much lower sensitivity than that of asthma-related diseases (0.481 vs. 0.995, p＜0.0001). Cohen's kappa for asthma-related disease was 0.976, and that for COPD-related disease was 0.621.
Conclusion
Self-perception of asthma-related disease was adequately high, whereas that of COPD-related disease was low. The prevalence rates of BA, COPD, ACO, and CVA in our study were 10.0%, 11.8%, 2.6%, and 0.9%, respectively. An increase in the perception of COPD may help improve community healthcare for respiratory diseases.
Keywords: patients' disease perception, disease prevalence, Japanese age distribution, Medical Support Center, chronic obstructive pulmonary disease
Introduction
In Japanese adults, the prevalence of bronchial asthma (BA) is 3.4-10.1% (1,2), chronic obstructive pulmonary disease (COPD) is 8.6-16% (3), and asthma and COPD overlap (ACO) is 1-5%, which is more than 10% of patients with asthma or COPD (4-8). However, few reports on the general prevalence of cough variant asthma (CVA), a subtype of asthma characterized by cough without wheezing, are available (1,9-11). Several of these reports included the largest number of subjects in the 50-59 years age group, which may not reflect the actual situation in Japan, which has a large population of older adults (2,3). Furthermore, reports on the perception of BA, CVA, COPD, and ACO are limited (1,12).
If some patients are unaware of their own disease because of a lack of subjective symptoms or unstable memory, the correct basic patient medical status may not be obtained. An early diagnosis and treatment are essential for disease management, and chronic respiratory diseases are no exception (13-15). Studies in the adult population have included accurate interviews, respiratory function tests, and diagnoses by a medical specialist, which may provide a consistent assessment of actual self-perception. We adopted a preoperative management system in which patients undergoing standby general anesthesia surgery were interviewed by a nurse at the Medical Support Center and consulted a specialized respiratory specialist if they had any self-reported diagnoses of BA, CVA, COPD, chronic bronchitis, emphysema, or ACO or had abnormalities in respiratory function tests (16).
In this study, we retrospectively investigated the prevalence of BA, CVA, COPD, and ACO as well as the discrepancy between disease perception and medical diagnoses using 229 datasets matched to the sex and age distribution of the Japanese population from 1,000 adult cases.
Materials and Methods
1. Subjects
A total of 229 datasets, which were matched to the distribution of sex and age of the Japanese population in 2016, from 1,000 patients were included. Patients' disease self-perception and final respiratory disease diagnoses (BA, CVA, COPD, and ACO) were identified (17) (Table 1). The patients received general anesthesia at Nagasaki University Hospital between July 2014 and July 2017.
Table 1.
Subject Characteristics.
| Total, n=229 | Asthma, n=15 | Asthma related diseases*, n=23 | COPD, n=21 | COPD related diseases**, n=27 | Healthy, n=181 | |
|---|---|---|---|---|---|---|
| Age | 57.5±16.1 | 49.3±17.0 | 56.0±19.0 | 64.7±8.4 | 67.3±10.0 | 56.7±16.3 |
| Men/ Women | 111/118 | 5/10 | 8/15 | 18/3 | 21/6 | 81/100 |
| Smoking habit, never/past/current | 126/52/51 | 9/4/2 | 12/8/3 | 2/7/12 | 2/12/13 | 113/35/33 |
| Childhood asthma, yes/no | 9/220 | 6/9 | 8/14 | 0/21 | 2/25 | 0/181 |
| VC, L | 3.32±0.91 | 3.33±1.01 | 3.13±0.93 | 3.40±1.03 | 3.24±1.00 | 3.34±0.91 |
| FVC, L | 3.30±0.93 | 3.31±1.02 | 3.10±0.94 | 3.38±1.03 | 3.21±1.01 | 3.31±0.92 |
| FEV1, L | 2.56±0.77 | 2.48±0.75 | 2.25±0.74 | 2.21±0.68 | 2.09±0.67 | 2.64±0.77 |
| FEV1 to FVC, % | 77.7±9.2 | 75.1±10.7 | 72.4±10.3 | 66.0±9.1 | 65.6±8.6 | 79.8±7.7 |
| ACT | 21.5±2.1 | 21.5±2.1 | 21.5±2.1 | n.d. | n.d. | n.d. |
| FeNO, ppb | 30.0±25.6 | 44.1±36.1 | 37.6±32.8 | 21.0±5.5 | 23.0±13.9 | 17.3±5.0 |
| WBC, /μL | 6,118±1,855 | 6,760±2,533 | 6,277±2,268 | 6,914±1,790 | 6,688±1,702 | 5,999±1,807 |
| Neutrophil, % | 63.2±11.2 | 65.3±9.9 | 64.9±10.8 | 66.0±16.0 | 67.7±14.9 | 62.4±11.0 |
| Neutrophil number, /μL | 4,055±2,023 | 4,499±2,398 | 4,277±2,337 | 4,723±2,874 | 5,162±2,257 | 3,878±1,949 |
| Eosinophil, % | 2.62±2.36 | 3.71±3.12 | 2.94±2.78 | 2.53±2.24 | 2.02±1.99 | 2.50±2.31 |
| Eosinophil number, /μL | 159±164 | 236±257 | 179±223 | 202±200 | 153±175 | 147±148 |
VC: vital capacity, FVC: forced vital capacity, FEV1: forced expiratory volume in 1 second, ACT: asthma control test, FeNO: fractional exhaled nitric oxide, *: Asthma related diseases include asthma, ACO, and CVA. **: COPD related diseases include COPD and ACO. CVA: cough variant asthma, COPD: chronic obstructive pulmonary disease, ACO: asthma and COPD overlap. The numbers do not add up because some patients had overlapping conditions or 4 patients with other diseases are not included.
This study was approved by the Clinical Research Ethics Committee of Nagasaki University Hospital (18111933).
2. Self-perception of diseases
Patients' self-perceptions of past or present recognized BA, CVA, COPD, emphysema, chronic bronchitis, and ACO were obtained via interviews and recorded by nurses at the Medical Support Center.
3. Respiratory function test
Respiratory function tests were performed by a specialist technician using a spirometer (Chestac 6000; CHEST, Tokyo, Japan). Reversibility testing was performed when required.
4. The diagnosis of each disease
4.1. The diagnosis of BA
The diagnosis of BA was based on a history of having a diagnosis made by a physician and/or the previous presence of typical asthma-like symptoms (cough, wheezing, variable, or seasonal episodes) and respiratory function test results consistent with BA. If the diagnosis was difficult, the final diagnosis was determined by a specialist with reference to the peripheral blood eosinophil count, exhaled nitric oxide, bronchial hypersensitivity, and reversibility test with bronchodilators (1,10,11,18).
4.2. Definition of CVA
CVA was diagnosed based on the definition of Corrao et al.: dry cough lasting over eight weeks, with no wheezing or rhonchi during forced expiration, no evidence of dyspnea, and a normal respiratory function (19). If a diagnosis was difficult, it was determined by airway hyperresponsiveness to acetylcholine [≥15% decrease in forced expiratory volume in 1 s (FEV1)], ≥15% improvement in FEV1 after inhalation of 200 μg salbutamol, or confirmation of improvement of cough with bronchodilators (10,11). When necessary, the medical records were checked by an attending physician at the time of the previous diagnosis.
4.3. The diagnosis of COPD
The diagnosis of COPD was based on a history of smoking (≥ 10 pack-years), an FEV1-to-forced vital capacity ratio of ＜0.7 after inhalation of bronchodilators, and differential exclusion of other diseases (20).
4.4. The diagnosis of ACO
ACO has been proposed as a diagnostic criterion. In this study, ACO was defined as fulfilling the diagnoses of both BA and COPD according to the Japanese guidelines (21,22).
5. Statistical analyses
The prevalence of BA, CVA, COPD, and ACO was also assessed. The chi-square test was used to calculate the sensitivity and specificity of the self-recognition rate, i.e. the rate of concordance between self-reported disease and the final diagnosis (JMP 16.0; SAS Institute, Tokyo, Japan). A chi-square test was performed to compare the self-recognition rates for BA and COPD. The agreement between disease perception and diagnosis was evaluated using kappa statistics (JMP 16.0; SAS Institute).
Results
1. Confirmed diagnoses of all patients
In the database of 1,000 patients (220 men and 780 women; mean age, 59.0 [±15.7] years old), confirmed diagnoses included asthma-related diseases in 96 patients (80 BA, 7 CVA, and 9 ACO) and COPD in 84 patients (75 pure COPD and 9 ACO).
2. Match modification to Japanese age-sex distribution
The referral source departments varied, from breast and endocrine surgery to respiratory surgery, gastrointestinal surgery, obstetrics, gynecology, and others. Considering the bias by sex and age distribution, 229 datasets [men/women =111/118; mean age, 57.6 (±16.1) years old] that matched the Japanese age and sex distribution were included in the analysis [16] (Table 2 and Figure). The prevalence of BA (n=23), including CVA (n=2) and ACO (n=6), in 229 adults was 10.0%; CVA, 0.9% (8.7%); and ACO, 2.6%. The prevalence of COPD (n=27), including ACO (n=6), was 11.8% among 229 adults. The prevalence of ACO was 2.6% (BA: 28.6%; COPD: 22.2%).
Table 2.
Analyzed Dataset Distribution Adjusted to the Japanese Sex–age Population Structure.
| Men, age range | Women, age range | Total, n (%) | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 15-64 | 65-74 | 75< | Total | 15-64 | 65-74 | 75< | Total | ||
| Asthma | 5 | 0 | 0 | 5 | 7 | 1 | 2 | 10 | 15 (7) |
| CVA | 0 | 0 | 0 | 0 | 2 | 0 | 0 | 2 | 2 (1) |
| COPD | 13 | 3 | 2 | 18 | 0 | 2 | 1 | 3 | 21 (9) |
| ACO | 0 | 0 | 3 | 3 | 2 | 0 | 1 | 3 | 6 (3) |
| Other | 2 | 1 | 1 | 4 | 0 | 0 | 0 | 0 | 4 (2) |
| Healthy | 59 | 13 | 9 | 81 | 65 | 16 | 19 | 100 | 181 (79) |
| Total, n (%) | 79 (34) | 17 (7) | 15 (7) | 111 (48) | 76 (33) | 19 (8) | 23 (10) | 118 (52) | 229 (100) |
CVA: cough variant asthma, COPD: chronic obstructive pulmonary disease, ACO: asthma and COPD overlap
Figure.
Considering the bias by sex and age distribution, 229 datasets [men/women=111/118; mean age, 57.6 (±16.1) years old] that matched the Japanese age and sex distribution were included in the analysis. The prevalence of asthma (n=23), including CVA (n=2) and ACO (n=6), in 229 adults was 10.0%, that of CVA was 0.9% (8.7% of asthma), and that of ACO was 2.6%. The prevalence of COPD (n=27), including ACO (n=6), in 229 adults was 11.8%, and that of ACO was 2.6% (28.6% of asthma and 22.2% of COPD). CVA: cough variant asthma, COPD: chronic obstructive pulmonary disease, ACO: asthma and COPD overlap
3. Reliability of the self-perception of asthma-related diseases (BA, CVA, and ACO)
Table 3a shows self-perception and confirmed diagnoses of asthma-related diseases (BA, CVA, and ACO) in 229 individuals matched to the Japanese population distribution. Of the 24 patients who reported having asthma-related disease, 23 had a related disease (positive predictive value of 95.8%). None of the 205 patients who reported no asthma-related disease had any asthma-related disease (negative predictive value of 100%). Of the three patients who reported having CVA, one was healthy without any asthma-related diseases. The perception of BA, CVA, and ACO for the diseases had a sensitivity of 1.00, specificity of 0.995, false-negative rate of 0, false-positive rate of 0.005, positive predictive value of 0.958, negative predictive value of 1.0, and disease prevalence of 0.10. The Cohen's kappa coefficient was 0.976 for asthma-related diseases.
Table 3a.
Self-perception and Confirmed Diagnoses of Asthma-related Diseases (BA, CVA, or ACO), n=229
| Confirmed diagnosis is BA, CVA or ACO | |||
|---|---|---|---|
| Perception disease is BA, CVA or ACO | Yes | No | |
| Yes | 23 | 1 | 24 |
| No | 0 | 205 | 205 |
| 23 | 206 | 229 | |
Cohen’s kappa was 0.976 for asthma-related disease. BA: bronchial asthma, CVA: cough variant asthma, ACO: asthma and COPD overlap
4. Reliability of self-perception of COPD-related diseases (COPD and ACO)
Table 3b shows the self-perception and confirmed diagnoses of COPD and ACO; 14 of the 217 patients who reported that they had neither COPD nor ACO had COPD or ACO (negative predictive value, 93.5%). Of the 27 patients with COPD or ACO, only 48.1% (n=13) had a perception of COPD or ACO (sensitivity, 0.481). More than half of the patients with COPD or ACO had no perception of COPD or ACO (false-negative rate, 0.519). Only 33.3% (n=2) of the 6 patients with asthma and COPD (equal to ACO) self-identified as having ACO.
Table 3b.
Self-perception and Confirmed Diagnoses of COPD-related Diseases (COPD or ACO), n=229.
| Confirmed diagnosis is COPD or ACO | |||
|---|---|---|---|
| Perception disease is COPD or ACO | Yes | No | |
| Yes | 13 | 0 | 13 |
| No | 14 | 202 | 216 |
| 27 | 202 | 229 | |
Cohen’s kappa was 0.621 for COPD-related disease. COPD: chronic obstructive pulmonary disease, ACO: asthma and COPD overlap
The perception of COPD or ACO for the diseases had a sensitivity of 0.481, specificity of 1.0, false-negative rate of 0.519, false-positive rate of 0, positive predictive rate of 1.0, negative predictive rate of 0.935, and prevalence of 0.117. Cohen's kappa coefficient was 0.621 for COPD-related diseases.
5. A comparison of disease perception sensitivity between patients with asthma- and COPD-related diseases
The sensitivities of disease perception of asthma- and COPD-related diseases were compared (Table 4). The perception of COPD-related diseases had a much lower sensitivity than that of asthma-related diseases (0.481 vs. 0.995, Pearson's chi-square value, 15.56; p＜0.0001).
Table 4.
Comparison of Sensitivity of Perception for Confirmed Diagnosis between Asthma-related and COPD-related Diseases.
| Asthma-related diseases, n=23 | COPD-related diseases, n=27 | p value | |
|---|---|---|---|
| Matched, n (%) | 23 (100) | 13 (48.1) | <0.0001 |
The perception of COPD-related diseases had a much lower sensitivity than that of asthma-related diseases (0.481 vs. 1.00, Pearson’s chi-square value, 15.56; p<0.0001).
Discussion
In this study, self-perception was relatively high for asthma-related diseases but much lower for COPD-related diseases (Cohen's kappa: 0.976 and 0.621, respectively). The frequency of BA was 10.0%, that of COPD was 11.8%, that of ACO was 2.6% (28.6% of BA and 22.2% of COPD), and that of CVA was 0.9% (8.7% of BA).
Self-perception of asthma was reliable, with a positive predictive value of 95.8% and a negative predictive value of 100%. CVA is considered an early stage of classic asthma and should be managed with anti-inflammatory therapy (10). It is difficult to diagnose, and its prevalence is rarely reported. The symptoms, airway inflammation, and airway hyperresponsiveness of CVA were milder than those of BA. For reference, CVA accounted for 8.7% of asthma cases or ＜1% of all cases in the present study, although this study may not be an accurate representation of the ratio of Japanese people. There were concerns about the overdiagnosis of CVA, but it wasn't as significant (12). A recent report indicated that 52.7% of chronic cough cases are associated with CVA; however, the ratio to asthma has not been clarified (23).
Although the estimated number of patients with COPD is more than 5 million in Japan, only a few hundred thousand have been treated (3). Awareness of the disease is difficult, and COPD is often undiagnosed and untreated without discontinuation of smoking (20). In the present study, the perception was quite satisfactory for BA but was much worse for COPD. The use of spirometry in primary care is not common, and the clinical diagnosis of COPD, chronic bronchitis, or emphysema may not be sufficiently reliable (15). Both patients and doctors may have an insufficient awareness of COPD.
The early diagnosis and treatment of COPD may also help reduce respiratory decline (24). Although several reports have shown that early COPD treatment prolongs the lifespan and improves the quality of life, a low level of perception of COPD was observed in the present study. Therefore, it is important to spread social recognition of smoking problems and COPD. Of note, COPD causes 16,000 deaths annually worldwide, and discontinuation of smoking slows COPD progression. As patients' perceptions of COPD are low (12), they cannot accurately inform their doctors of their own medical status. This can result in clinical inertia (25).
The prognosis of ACO is poor (26,27), and a proper diagnosis is necessary (28). In the present study, the prevalence of ACO was 2.6% (30.0% for BA and 22% for COPD). Tamada et al. reported that ACO accounted for 16.3% of COPD cases (8). If a patient has ACO, inhaled corticosteroid/long-acting β2-agonist/long-acting muscarinic antagonist treatment (triple therapy) should be administered. The Japanese guidelines for asthma do not list the frequencies of ACO or CVA (1). Of the 19 patients whose perception was BA only in this study, 4 did not recognize their own COPD. If COPD is not observed, the patient may not benefit from long-acting muscarinic antagonists (20). This may be due to a lack of awareness of ACO and could hinder the widespread use of triple therapy (29). The Global Initiative for Chronic Obstructive Lung Disease guidelines (20) states, “We no longer refer to asthma and COPD overlap (ACO); instead, we emphasize that asthma and COPD are different disorders, although they may share some common treatable traits and clinical features. Asthma and COPD can coexist in individual patients. If a concurrent diagnosis of asthma is suspected, pharmacotherapy should primarily follow asthma guidelines, but pharmacological and non-pharmacological approaches may also be needed for COPD.”
Several limitations associated with the present study warrant mention. First, because this study was retrospective in nature, the diagnosis of CVA was particularly difficult when the disease was already in remission. Whenever possible, we resolved these discrepancies by interviewing the attending physicians. Second, the demographics used in this study were referenced from 2016, and follow-up and comparison of new data should be considered in future studies. Third, previous cross-sectional studies have shown that the prevalence of COPD in Japan is high among people ≥65 years old (30,31). However, in the present study, there were 13 cases in people ＜64 years old and only 5 cases in people ≥65 years old, showing a clear difference in trend. This is probably because the study was limited to patients scheduled for general anesthesia, excluding elderly patients who were not suitable for surgery and those with a low lung function. The prevalence was presented for reference; however, even when accounting for this selection bias, there was generally no marked difference from previous reports (1-3).
Conclusions
In the Japanese population, the diagnosis and self-perception of BA are adequately high, but those of COPD are low. This information may help improve community health care.
The authors state that they have no Conflict of Interest (COI).
Acknowledgments
The authors thank all of the patients. The authors also thank the MSC nurses Mayumi Yamamura, Midori Watarizaki, Aiko Takamura, Tomo Morizaki, Marie Takeda, Maria Urakawa, and Hiroaki Aihara for their assistance with data management.
References
- 1.Nakamura Y, Tamaoki J, Nagase H, et al. Japanese guidelines for adult asthma 2020. Allergol Int 69: 519-548, 2020. [DOI] [PubMed] [Google Scholar]
- 2.Fukutomi Y, Taniguchi M, Watanabe J, et al. Time trend in the prevalence of adult asthma in Japan: findings from population-based surveys in Fujieda City in 1985, 1999, and 2006. Allergol Int 60: 443-448, 2011. [DOI] [PubMed] [Google Scholar]
- 3.Fukuchi Y, Nishimura M, Ichinose M, et al. COPD in Japan: the Nippon COPD Epidemiology study. Respirology 9: 458-465, 2004. [DOI] [PubMed] [Google Scholar]
- 4.Postma DS, Rabe KF. The asthma-COPD overlap syndrome. N Engl J Med 373: 1241-1249, 2015. [DOI] [PubMed] [Google Scholar]
- 5.Matsumoto K, Seki N, Fukuyama S, et al. Prevalence of asthma with airflow limitation, COPD, and COPD with variable airflow limitation in older subjects in a general Japanese population: the Hisayama Study. Respir Investig 53: 22-29, 2015. [DOI] [PubMed] [Google Scholar]
- 6.Inoue H, Nagase T, Morita S, Yoshida A, Jinnai T, Ichinose M. Prevalence and characteristics of asthma-COPD overlap syndrome identified by a stepwise approach. Int J Chron Obstruct Pulmon Dis 12: 1803-1810, 2017. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 7.Mendy A, Forno E, Niyonsenga T, Carnahan R, Gasana J. Prevalence and features of asthma-COPD overlap in the United States 2007-2012. Clin Respir J 2018 12: 2369-2377, 2018. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 8.Tamada T, Sugiura H, Takahashi T, et al. Biomarker-based detection of asthma-COPD overlap syndrome in COPD populations. Int J Chron Obstruct Pulmon Dis 10: 2169-2176, 2015. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 9.Gibson PG, Fujimura M, Niimi A. Eosinophilic bronchitis: clinical manifestations and implications for treatment. Thorax 57: 178-182, 2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 10.Niimi A. Geography and cough aetiology. Pulm Pharmacol Ther 20: 383-387, 2007. [DOI] [PubMed] [Google Scholar]
- 11.Shimoda T, Obase Y, Kishikawa R, Iwanaga T, Miyatake A, Kasayama S. The fractional exhaled nitric oxide and serum high sensitivity C-reactive protein levels in cough variant asthma and typical bronchial asthma. Allergol Int 62: 251-257, 2013. [DOI] [PubMed] [Google Scholar]
- 12.Tiemensma J, Gaab E, Voorhaar M, Asijee G, Kaptein AA. Illness perceptions and coping determine quality of life in COPD patients. Int J Chron Obstruct Pulmon Dis 11: 2001-2007, 2016. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13.Mukae H, Kaneko T, Obase Y, et al. The Japanese respiratory society guidelines for the management of cough and sputum (digest edition). Respir Investig 59: 270-290, 2021. [DOI] [PubMed] [Google Scholar]
- 14.Baiardini I, Contoli M, Corsico AG, et al. Exploring the relationship between disease awareness and outcomes in patients with chronic obstructive pulmonary disease. Respiration 100: 291-297, 2021. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 15.Cazzola M, Puxeddu E, Bettoncelli G, et al. The prevalence of asthma and COPD in Italy: a practice-based study. Respir Med 105: 386-391, 2011. [DOI] [PubMed] [Google Scholar]
- 16.Yamaguchi E, Obase Y, Fukahori S, et al. Preoperative respiratory intervention eliminated the operation cancelations of lobectomy surgery. J Med Syst 46: 29, 2022. [DOI] [PubMed] [Google Scholar]
- 17.Statistics Bureau, Ministry of Internal Affairs and Communications . Statistical handbook of Japan 2017 [Internet]. [cited 2024 Aug 6]. https://www.stat.go.jp/english/data/handbook/pdf/2017all.pdf
- 18.Global Initiative for Asthma. 2023 GINA report, Global Strategy for Asthma management and prevention [Internet]. [cited 2024 Aug 6]. https://ginasthma.org/2023-gina-main-report/
- 19.Corrao WM, Braman SS, Irwin RS. Chronic cough as the sole presenting manifestation of bronchial asthma. N Engl J Med 300: 633-637, 1979. [DOI] [PubMed] [Google Scholar]
- 20.Global Initiative for Chronic Obstructive Lung Disease (GOLD). 2023 GOLD report: global strategy for prevention, diagnosis and management of COPD: 2023 report [Internet]. [cited 2024 Aug 6]. https://www.goldcopd.org/2023-gold-report-2/
- 21.Yamamura K, Hara J, Kobayashi T, et al. The prevalence and clinical features of asthma-COPD overlap (ACO) definitively diagnosed according to the Japanese Respiratory Society Guidelines for the Management of ACO 2018. J Med Invest 66: 157-164, 2019. [DOI] [PubMed] [Google Scholar]
- 22.Uchida A, Sakaue K, Inoue H. Epidemiology of asthma-chronic obstructive pulmonary disease overlap (ACO). Allergol Int 67: 165-171, 2018. [DOI] [PubMed] [Google Scholar]
- 23.Ishiura Y, Fujimura M, Ogawa H, et al. Prevalence and causes of chronic cough in Japan. Respir Investig 62: 442-448, 2024. [DOI] [PubMed] [Google Scholar]
- 24.Wedzicha JA, Decramer M, Ficker JH, et al. Analysis of chronic obstructive pulmonary disease exacerbations with the dual bronchodilator QVA149 compared with glycopyrronium and tiotropium (SPARK): a randomised, double-blind, parallel-group study. Lancet Respir Med 1: 199-209, 2013. [DOI] [PubMed] [Google Scholar]
- 25.Celli B, Blasi F, Gaga M, et al. Perception of symptoms and quality of life - comparison of patients' and physicians' views in the COPD MIRROR study. Int J Chron Obstruct Pulmon Dis 12: 2189-2196, 2017. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Soler-Cataluña JJ, Cosío B, Izquierdo JL, et al. Consensus document on the overlap phenotype COPD-asthma in COPD. Arch Bronconeumol 48: 331-337, 2012. [DOI] [PubMed] [Google Scholar]
- 27.Suzuki M, Makita H, Konno S, et al. Asthma-like features and clinical course of chronic obstructive pulmonary disease. An analysis from the Hokkaido COPD cohort study. Am J Respir Crit Care Med 194: 1358-1365, 2016. [DOI] [PubMed] [Google Scholar]
- 28.Miravitlles M, Alvarez-Gutierrez FJ, Calle M, et al. Algorithm for identification of asthma-COPD overlap: consensus between the Spanish COPD and asthma guidelines. Eur Respir J 49: 1700068, 2017. [DOI] [PubMed] [Google Scholar]
- 29.Vogelmeier CF, Criner GJ, Martínez FJ, et al. Global strategy for the diagnosis, management, and prevention of chronic obstructive lung disease 2017 report: gold executive summary. Arch Bronconeumol 53: 128-149, 2017. [DOI] [PubMed] [Google Scholar]
- 30.Tanimura K, Sato S, Fuseya Y, et al. Quantitative assessment of erector spinae muscles in patients with chronic obstructive pulmonary disease. Novel chest computed tomography-derived index for prognosis. Ann Am Thorac Soc 13: 334-341, 2016. [DOI] [PubMed] [Google Scholar]
- 31.Suzuki M, Makita H, Ito YM, et al.; Hokkaido COPD Cohort Study Investigators . Clinical features and determinants of COPD exacerbation in the Hokkaido COPD cohort study. Eur Respir J 43: 1289-1297, 2014. [DOI] [PubMed] [Google Scholar]