Funding for this research was provided by:
Health Department of Sichuan Province (18PJ224)
Received: 8 March 2019
Accepted: 20 September 2019
First Online: 15 October 2019
Ethics approval and consent to participate
: The study obtained the approval by the Ethics Committee, West China school of Medicine/ West China Hospital, Sichuan University. Informed consent from all participants was obtained prior to the study.
: Not applicable. All results are reported as aggregated data.
: The authors declare that they have no competing interests.