Text and Data Mining valid from 2018-07-16
Received: 12 April 2018
Accepted: 5 July 2018
First Online: 16 July 2018
Ethics approval and consent to participate
: This study was approved by the ethics committee of The Third Affiliated Hospital of Zhengzhou University.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.