Funding for this research was provided by:
Yunnan Provincial Department of Health (L-201201)
Received: 10 September 2019
Accepted: 4 February 2020
First Online: 12 February 2020
Ethics approval and consent to participate
: This study was approved by the Medical Ethics Committee of First People’s Hospital of Yunnan Province (No. 2015-KY052). All procedures were in accordance with the ethical standards of the national research committee and with the 1964 Helsinki declaration and its later amendments. All participants provided written informed consent.
: Not applicable.
: The authors declare that they have no competing interests.