Funding for this research was provided by:
Youth Innovation in Medical Research Subject in Sichuan Province of China (Q17020)
Chengdu Science and Technology Bureau (2018JY0383)
Received: 22 April 2019
Accepted: 16 April 2020
First Online: 1 May 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Committee Public Health Clinical Center of Chengdu, Sichuan, China [AF/SC-08/01.0], project approval No.[2017Y] 025. As this was a retrospective study and all patient information used in this study was routinely collected through the mandatory notification system, the requirement for informed consent was waived by the ethics committee.
: Not applicable.
: The authors declare no conflicts of interest.