Received: 4 July 2018
Accepted: 18 June 2019
First Online: 26 June 2019
Ethics approval and consent to participate
: Ethical approval was granted by the Ethics Committee of the Second Hospital of Shandong University (KYLL-2017(KJ)P-0003) and was retrospectively registered in Chinese Clinical Trial Registry (registration number: ChiCTR-IPR-17012368). Only the participants who signed the informed consent document were included in the study.
: Not applicable.
: Xiaosheng Dong, Xiangren Yi, Dezong Gao, Zan Gao, Shuyuan Huang, Mengyao Chao, Wenxin Chen, Meng Ding have stated explicitly that there is no conflict of interest in connection with this article.