Funding for this research was provided by:
National Natural Science Foundation of China (81601276)
the special fund for clinical research of the Chinese Medical Association (16020220638)
Received: 6 May 2019
Accepted: 5 July 2019
First Online: 18 July 2019
Ethics approval and consent to participate
: The study was approved by the Ethical Committee of Yantai Yuhuangding Hospital.
: Not applicable.
: The authors declare that they have no competing interests.