Received: 27 February 2019
Accepted: 4 July 2019
First Online: 22 July 2019
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 enrolled in the investigation.
: All the patients in this study have given their informed consent for the article to be published.
: The authors declare that they have no competing interests.