Funding for this research was provided by:
Fundamental Research Funds for the Central Universities (lzujbky-2019-cd06)
Received: 23 December 2018
Accepted: 31 March 2020
First Online: 10 April 2020
Ethics approval and consent to participate
: This study was conducted in accordance with the declaration of Helsinki. Informed consent from the patients was waived because of the retrospective nature of this study, and this study was approved by Institutional Ethnic Committee of the Lanzhou University second hospital (2018A-090).
: Not Applicable.
: All authors declare no conflicts of interest.