A Prospective Cohort Study of Asthma and COPD Overlap in Japanese COPD Patients Using the Diagnostic Criteria of The Japanese Respiratory Society

This study is a multicentered and non-interventional prospective cohort study. Study centers shall be the institutions where the examinations, adopted in the ACO diagnostic criteria9) from The Japanese Respiratory Society, are performed at least once a year as a part of their regular practice. Physicians participating in the study will consecutively register by means of central registration outpatients who have the characteristics of COPD in the ACO diagnostic criteria9) from The Japanese Respiratory Society, and who have been confirmed to satisfy the inclusion criteria whereas not violating the exclusion criteria. The physicians will collect data including the patients' results from medical examinations by using the ACO diagnostic criteria, at each time point (on the registration, after 1 year, and after 2 years). Electronic case report forms completed by participating physicians and questionnaires completed by patients will be used to collect data.

Inclusion criteria

• Patients from whom written consent to participate in this study has been obtained
• Patients ≥40 years old
• Patients with FEV1/FVC ratio <70% after bronchodilator inhalation within the past year or on the registrationa
• Patients who satisfy any one of the following items:

• Smoking history (≥10 pack-years) or comparable air pollution exposure on the registrationa 2) Presence of the low attenuation area on chest CT demonstrating emphysematous alteration within the past year or on the registration a,b, 3) Impaired pulmonary diffusing capacity (%DLCO <80% or %DLCO/VA <80%) within the past year or on the registrationa 4) Patients deemed capable of visiting their study center in Japan at least once a year on an outpatient basis

Exclusion criteria

• Patients who participated in other interventional studies such as clinical trial within the last 8 weeks.
• Patients who are unsuitable for their enrollment in this study, judged by the participating physician, because they cannot comply with the procedures, restrictions, and requirements of this study (e.g., patients with dementia).
• Patients with exacerbationsa of COPD or asthma within the last 8 weeks. a COPD exacerbation: State of increased shortness of breathing, increased cough and sputum, and occurrence or exacerbation of chest discomfort that requires a change of treatment during the stable phase. However, exacerbation preceded by other disorders (e.g., heart failure, pneumothorax, pulmonary thromboembolism) is excluded.

Asthma exacerbation: Occurrence of paroxysmal/variable cough/sputum/wheezing/dyspnea caused by various factors including respiratory infection.

• Patients carrying following disorders that should be distinguished from COPD or asthma:

Diffuse panbronchiolitis, congenital sinobronchial syndrome, occlusive panbronchiolitis, bronchiectasis, pulmonary tuberculosis, pneumoconiosis, lymphangioleiomyomatosis, congestive heart failure, interstitial lung disease, lung cancer, laryngitis, epiglottitis, vocal cord dysfunction, intratracheal tumor, airway foreign substance, tracheomalacia, bronchial tuberculosis, pulmonary thromboembolism, cough induced by drug such as angiotensin-converting enzyme inhibitor, spontaneous pneumothorax, hyperventilation syndrome, psychogenic cough