Funding for this research was provided by:
Sichuan Province Science and Technology Support Program (2018DJPT0011)
Health and Family Planning Commission of Sichuan Province (17PJ506)
the Affiliated Hospital of Luzhou Medical College Science Foundatio (14035)
Received: 20 April 2020
Accepted: 5 August 2020
First Online: 14 August 2020
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of the Affiliated Hospital of Southwest Medical University (project no. KY2020043). This is a retrospective study. The need for informed consent was waived by the Clinical Research Ethics Committee.
: Not applicable.
: The authors declare that they have no competing interests.