Government of the People's Republic of China - China-Japan Friendship Hospital, Government of the People's Republic of China - Center of Respiratory Medicine, Government of the People's Republic of China - China-Japan Friendship Hospital, World Health Organization (WHO) - Collaborating Center for Tobacco Cessation and Respiratory Diseases Prevention, World Health Organization (WHO) - Collaborating Center for Tobacco Cessation and Respiratory Diseases Prevention, World Health Organization (WHO) - Collaborating Center for Tobacco Cessation and Respiratory Diseases Prevention, Government of the People's Republic of China - Center of Respiratory Medicine, Capital Medical University, affiliation not provided to SSRN, affiliation not provided to SSRN, Government of the People's Republic of China - Center of Respiratory Medicine, Government of the People's Republic of China - Center of Respiratory Medicine, Capital Medical University, World Health Organization (WHO) - Collaborating Center for Tobacco Cessation and Respiratory Diseases Prevention, Government of the People's Republic of China - Center of Respiratory Medicine and Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC) - State Key Laboratory of Medical Molecular Biology