Details of ethics approval
The research protocol used in this study was reviewed and approved by
the Institutional Ethics Committee of Peking University First Hospital:
Approval number: 2019[578], Date: 01/06/2019. As this is a
retrospective observational study, the Medical Ethical Committee waived
the informed consent requirement for this study. Approval to obtain
clinical data from the hospital database was obtained from the office of
the medical director of the hospital. All patient information was kept
confidential.