Text and Data Mining valid from 2020-03-17
Received: 24 January 2019
Accepted: 18 February 2020
First Online: 17 March 2020
Ethics approval and consent to participate
: The study was approved and registered by the local ethics committee of the First Affiliated Hospital of Chongqing Medical University (Reg. No. 2018–005), no informed consent had to be obtained because of retrospective data collection.
: Not applicable.
: The authors declare that they have no competing interests.