Zhai, Xiaodong
Zhou, Ming
Chen, Hongwei
Tang, Qunfeng
Cui, Zhimin
Yao, Yong
Yin, Qihua
Article History
Received: 24 August 2018
Accepted: 7 January 2019
First Online: 25 January 2019
Compliance with ethical standards
:
: No conflict of interest exists in the submission of this manuscript, and manuscript is approved by all authors for publication. I would like to declare on behalf of my co-authors that the work described was original research that has not been published previously, and not under consideration for publication elsewhere, in whole or in part. All the authors listed have approved the manuscript that is enclosed.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
: This retrospective study was approved by our institutional review board, and the requirement for informed consent was waived.