Funding for this research was provided by:
Taishan Scholars Program of Shandong Province (ts201511109 and tsqn20161079)
Qingdao Key Health Discipline Development Fund
Received: 6 October 2020
Accepted: 24 January 2021
First Online: 5 February 2021
Ethics approval and consent to participate
: This study was approved by the ethic committee of Qingdao Municipal Hospital. Written informed consent form was obtained from all participants or their guardians. This study was conducted in accordance with the Declaration of Helsinki and approved by the Institutional Ethics Committees of Qingdao Municipal Hospital.
: Not applicable.
: The authors declare that they have no competing interests.