Funding for this research was provided by:
the Special Research Fund for Central Universities, Peking Union Medical College (2018PT33001)
Received: 24 July 2019
Accepted: 27 February 2020
First Online: 12 March 2020
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of Peking Union Medical College Hospital (S-K540). All included subjects gave their written informed consent forms to participate in the study.
: All subjects gave written consent for their accounts to be anonymously published.
: The authors declare that they have no competing interests.