Funding for this research was provided by:
grants from the Ministry Science and Technology of China (2016YFC0901205, 2016YFC0901200)
research grants from Health and Family Planning Commission of Sichuan Province (16129)
Received: 1 January 2020
Accepted: 9 May 2020
First Online: 19 May 2020
Ethics approval and consent to participate
: The study was approved by the ethics committee of the Affiliated Hospital of Southwest Medical University. Written informed consent was obtained before the data collection and analysis.
: Not applicable.
: The authors declare that they have no competing interests.