Funding for this research was provided by:
National Natural Science Foundation of China (81571645)
Sichuan Province Special Project for Youth Team of Science and Technology Innovation (2015TD0029)
Construction Plan for Scientific Research Team of Sichuan Provincial Colleges and Universities (15TD0023)
Received: 17 May 2019
Accepted: 13 September 2019
First Online: 16 October 2019
Ethics approval and consent to participate
: This retrospective study was approved by the institutional review board of the Affiliated Hospital of North Sichuan Medical College. The patient consent for the study was waived as it is retrospective.
: All authors gave consent for the publication of this paper.
: The authors declare that they have no competing interests.