Eiko Suzuki

Introduction Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the world and is associated with increasing economic costs and social burdens.1,2 Although spirometry is the gold standard for the clinical measurement of COPD, it does not provide sufficient essential information on exacerbation, leading to worsening respiratory impairment and prognosis.3 Exacerbation of COPD decreases the quality-of-life, causes respiratory dysfunction, and adversely affects...