Received: 28 December 2019
Accepted: 5 May 2020
First Online: 20 May 2020
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of the Affiliated Hospital of Qingdao University. Written informed consent was obtained from all patients. No children (under 16 years old) were included in this study.
: Not applicable.
: The authors declare that they have no competing interests.