Text and Data Mining valid from 2019-10-30
Received: 12 June 2019
Accepted: 22 September 2019
First Online: 30 October 2019
Ethics approval and consent to participate
: Informed consent was obtained from each participant, and this study was approved by the institute Medical Ethics Committee of Hebei Medical University, Fourth Hospital (2018MEc038).
: Not applicable
: The authors declare that they have no competing interests.