Funding for this research was provided by:
National Natural Science Foundation of China (71874043;71473063)
Social Science Foundation Research Projects of Beijing (16JDGLA028)
Innovative Research Projects of Graduate Students at Harbin Medical University (YJSCX2017-15HYD)
Received: 6 September 2018
Accepted: 21 May 2019
First Online: 30 May 2019
Ethics approval and consent to participate
: The study was approved by the Institutional Review Board of Harbin Medical University. We obtained the consent of each hospital involved in the research process. All participants were guaranteed anonymity and the option not to participate and we provided informed consent to the medical staff before the survey (Project Identification Code: HMUIRB2014005).
: This study has obtained consent to publish from the participants to report individual data.
: The authors declare that they have no competing interests.