Text and Data Mining valid from 2019-01-30
Received: 25 June 2018
Accepted: 16 January 2019
First Online: 30 January 2019
Compliance with Ethical Standards
: All authors declare 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. This retrospective study was approved by our internal IRB board.
: As this study was retrospective, no informed consent was obtained.