Funding for this research was provided by:
the Teaching Quality Project of Sun Yat-sen University (80000-18832601)
Received: 21 May 2019
Accepted: 27 September 2019
First Online: 21 October 2019
Ethics approval and consent to participate
: The ethics committee of the First Affiliated Hospital, Sun Yat-sen University has approved the study. For the convenience of actual operation, verbal consent was obtained from the study participants, which was approved by the ethics committee.
: Not applicable.
: The authors declare that they have no competing interests.