Text and Data Mining valid from 2019-07-18
Received: 20 March 2019
Accepted: 26 June 2019
First Online: 18 July 2019
Compliance with ethical standards
: No other potential conflict of interest relevant to this article was reported.
: 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 analysis was approved by the Ethics Committee of Xijing Hospital (Approval No. KY20173008–1), and the informed consent was waived.