Text and Data Mining valid from 2019-08-30
First Online: 30 August 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: 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.
: The Institutional Review Board waived the requirement for informed consent for this retrospective study.