Funding for this research was provided by:
National Natural Science Foundation of China (81703324)
China Scholarship Council (201808535098)
Text and Data Mining valid from 2019-08-07
Received: 5 September 2018
Accepted: 31 July 2019
First Online: 7 August 2019
Ethics approval and consent to participate
: This study was approved by Institutional Research Ethics Board of Kunming University. Because of the retrospective nature, plus no individually identifiable or sensitive information was involved, informed consents from all patients had been waived.
: Not applicable.
: The authors declare that they have no competing interests.