Text and Data Mining valid from 2020-03-30
Received: 1 February 2020
Accepted: 23 March 2020
First Online: 30 March 2020
Ethics approval and consent to participate
: The study was approved by the ethics committee of Xiangya Hospital of Central South University (no. 2018121140). Patient consent was not required to review their medical records by the ethics committee of Xiangya Hospital of Central South University because of its retrospective design, and exemption from informed consent did not adversely affect the health and rights of subjects. This study kept confidentiality of patient data and strictly complied with the Declaration of Helsinki and its later amendments or comparable ethical standards.
: Not applicable.
: The authors declare that they have no competing interests.