Received: 9 December 2018
Accepted: 5 November 2019
First Online: 14 November 2019
Ethics approval and consent to participate
: This study was approved by the ethics committee of Jinan Central Hospital Affiliated to Shandong University. Written informed consent was obtained from all subjects as well as parental consent for subjects aged less than 18 years.
: Not Applicable.
: The authors declare that they have no competing interests.