Article History
Received: 25 January 2019
Accepted: 31 May 2019
First Online: 10 June 2019
Compliance with ethical standards
:
: Our study was approved by the ethics committee of the Affiliated Yantai Yuhuangding Hospital of Qingdao University.
: Informed consent was signed by all patients.
Free to read: This content has been made available to all.