Received: 8 May 2018
Accepted: 30 January 2019
First Online: 4 February 2019
Ethics approval and consent to participate
: The institutional review board of our hospital approved this retrospective study (ID; 018–0038), and the requirement to obtain informed consent was waived. 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.
: Not applicable.
: The authors declare that they have no competing interests.
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