Funding for this research was provided by:
grants from the Ministry Science and Technology of China (2016YFC0901200, 2016YFC0901205)
research grants from Health and Family Planning Commission of Sichuan Province (16129)
Received: 15 May 2020
Accepted: 28 February 2021
First Online: 10 March 2021
: The retrospective study was reviewed and approved by the human research ethics committee of the Affiliated Hospital of Southwest Medical University in accordance with the 1975 Declaration of Helsinki, and verbal informed consents were obtained from all patients to participate in this study.
: Not applicable.
: The authors declare that they have no competing interests.