Background: COPD is currently the sixth leading cause of death worldwide and is projected to rank fifth in 2020 as a worldwide burden of disease according to a study published by the World Bank/World Health Organization.

• 背景：慢性阻塞性肺疾病(COPD)COPD是目前世界上第六大致死性疾病。 世界卫生组织(WHO)预计到2020年，COPD将成为世界范围内第五大负担的疾病。