Funding for this research was provided by:
Text and Data Mining valid from 2020-02-07
Received: 19 November 2019
Accepted: 22 January 2020
First Online: 7 February 2020
Compliance with ethical standards
: The local institutional ethical review board approved this study and waived the requirement for written informed consent due to its retrospective nature (waiver number 2014/563). All data was processed anonymously after retrieval from the medical files. All procedures performed in this study were in accordance with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: The authors declare that they have no conflict of interest.