Text and Data Mining valid from 2019-09-11
Received: 15 December 2018
Accepted: 21 May 2019
First Online: 11 September 2019
Compliance with ethics guidelines
: Meng Lv, Xiaohui Zhang, Lanping Xu, Yu Wang, Chenhua Yan, Huan Chen, Yuhong Chen, Wei Han, Fengrong Wang, Jingzhi Wang, Kaiyan Liu, Xiaojun Huang, and Xiaodong Mo declare no potential financial conflict of interest related to this manuscript. Informed consent was obtained from all patients or their guardians. The study was conducted in accordance with the <i>Declaration of Helsinki</i>. The study protocol was approved by the Ethics Committee of Peking University People’s Hospital.