Received: 19 December 2018
Accepted: 14 October 2019
First Online: 25 November 2019
Ethics approval and consent to participate
: Our study was a retrospective study in which all information was extracted electronically with the approval of the Ethics Committee of First Hospital of Shanxi Medical University. No patient agreed, but all data were analyzed anonymously.
: Not applicable.
: The authors declare that they have no competing interests.