Received: 22 November 2018
Accepted: 18 March 2019
First Online: 11 April 2019
Ethics approval and consent to participate
: All patients in our research provided informed consent before the treatment. All procedures in this research were performed in accordance with the principles of the Research Ethics Committee of the Affiliated Yantai Yuhuangding Hospital of Qingdao University and with the 1964 Helsinki Declaration and its amendments.
: Not applicable.
: The authors declare that they have no competing interests.
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