Funding for this research was provided by:
Natural Science Foundation of Beijing Municipality (7174337.)
Received: 8 January 2019
Accepted: 24 June 2020
First Online: 11 July 2020
Ethics approval and consent to participate
: The study was approved by the ethics committee of Peking Union Medical College Hospital (PUMCH). Written informed consent was obtained from a parent or guardian for all the participants under 16 years old. During the research, all participants’ medical records were de-identified and randomly re-numbered to protect their privacy.
: Not applicable.
: Cai Siyi, MD, Cui Liqiang, MD, Qiu Guixing, MD, Shen Jianxiong, MD, Zhang Jianguo declare that they have no competing interest.