Received: 25 March 2019
Accepted: 14 April 2019
First Online: 30 September 2019
Compliance with Ethical Standards
: Xiaoyang Jin, Lingyuan Meng, Zhao Yin, Haisheng Yu, Linnan Zhang, Weifeng Liang, Shouli Wang, Guanyuan Liu and Liguo Zhang declare that they have no conflicts of interest.
: This study was carried out with the approval of Beijing Chaoyang Hospital Affiliated with Capital Medical University Ethics Committee (2018-12-21-2).