Text and Data Mining valid from 2019-05-08
Received: 29 January 2019
Accepted: 2 May 2019
First Online: 8 May 2019
Compliance with ethical standards
: The authors declare no conflicts of interest—financial or otherwise. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
: Institutional review board (IRB) approval for this study was granted as outlined by the principles set by the Declaration of Helsinki and its later amendments or comparable ethical standards.
: Informed consent was waived for this investigation, as the study was of minimal risk and the data were blinded and retrospective.