Article History
Received: 18 November 2018
Accepted: 24 June 2019
First Online: 11 July 2019
Ethics approval and consent to participate
: Approval for the study was obtained from the institutional review board and the ethics committee, Peking Union Medical College Hospital (Institutional Review Board File No. S-K490). Participants’ consent was obtained in written form.
: Not applicable.
: The authors declare no conflict of interest.