Funding for this research was provided by:
National Natural Science Funding of China (71573181)
Received: 21 May 2019
Accepted: 16 September 2019
First Online: 17 October 2019
Ethics approval and consent to participate
: The study obtained approval of the institutional review committees of the Capital Medical University Medical Ethics Committee (number: 2015SY45). With institutional review board approval, all study participants gave verbal informed consent to participate. Written consent was not requested as the qualitative study participation was anonymous.
: Not applicable.
: The authors declare that they have no competing interests.