Text and Data Mining valid from 2019-11-08
Received: 17 June 2019
Accepted: 31 October 2019
First Online: 8 November 2019
Ethics approval and consent to participate
: The study was approved by the clinical research ethics committee of Nanfang Hospital of Southern Medical University. This was a retrospective study that did not need informed consent.
: Not applicable.
: The authors declare no competing interests.