Jiang, Feng
Hu, Linlin
Zhao, Ruiping
Zhou, Huixuan
Wu, Yinuo
Rakofsky, Jeffrey J.
Liu, Tingfang
Liu, Huanzhong
Liu, Yuanli
Tang, Yi-Lang
Article History
Received: 19 June 2019
Accepted: 15 November 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee (IRB) of the Public Health School of Peking Union Medical College, and all local ethics committees approved the study at each site. All study participants signed informed consent before participating in the survey.
: Not Applicable.
: The authors declare that they have no competing interests.