Funding for this research was provided by:
Supporting Project for High Caliber Teachers in Beijing Municipal Universities during the “13th Five-year Plan” (IDHT20170516)
Received: 12 October 2019
Accepted: 27 February 2020
First Online: 12 March 2020
Ethics approval and consent to participate
: The study ethics approval was granted from the local ethical committee of the Beijing Xuanwu Hospital, and the study was performed in accordance with the principles of the Declaration of Helsinki. Written informed consent was obtained from all patients.
: Not applicable.
: The authors declare that they have no competing interests.