Text and Data Mining valid from 2019-02-02
Received: 5 November 2018
Accepted: 6 January 2019
First Online: 2 February 2019
Compliance with ethical standards
: All 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.
: Institutional review board approval was obtained, and the need for informed consent was waived for the current retrospective study.