Funding for this research was provided by:
the Government-funded Specialist Leaders Foundation (361005)
Received: 17 April 2019
Accepted: 19 August 2019
First Online: 2 September 2019
Ethics approval and consent to participate
: All protocols were approved by the Ethics Board of the Third Hospital of Hebei Medical University (January 3, 2013), and all participants provided informed consent.
: Not applicable.
: The authors declare that they have no competing interests.