Funding for this research was provided by:
the Research Project on Educational and Teaching Reform of Central South University (2018jy098)
Received: 24 May 2019
Accepted: 29 October 2019
First Online: 14 November 2019
Ethics approval and consent to participate
: This study was performed in accordance with the Helsinki Declaration and was approved by the Second Xiangya Hospital Ethics Committee. The informed consent obtained from study participants was written.
: Not applicable.
: The authors declare that they have no competing interests.