Funding for this research was provided by:
2017 Annual Plan of Key Topics for Medical Science Research in Hebei Province (20171375)
Received: 1 August 2019
Accepted: 24 February 2020
First Online: 7 March 2020
Ethics approval and consent to participate
: The present study was approved by the Ethics Committee of Tangshan Gongren Hospital.
: Not applicable
: The authors declare that they have no competing interests.