Text and Data Mining valid from 2019-01-02
Received: 5 September 2018
Revised: 18 December 2018
Accepted: 19 December 2018
First Online: 2 January 2019
Compliance with ethical standards
: All authors have reviewed the manuscript. Authors have no conflict of interest to declare.
: The study was conducted after receiving written informed consent from patients. In addition, this study was approved by the Institutional Ethics Committee of Xuanwu Hospital, Capital Medical University, Beijing, China.