Received: 12 January 2020
Accepted: 24 June 2020
First Online: 29 June 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of the Affiliated Hospital of Xuzhou Medical University and conducted in accordance with the standards of the National Research Council. Written informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.