Text and Data Mining valid from 2019-11-06
Received: 23 April 2019
Accepted: 15 October 2019
First Online: 6 November 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: This retrospective analysis was approved by the ethic committee of the university of Ulm, Germany. Number 133/16.
: Informed consent was not possible in this study due to retrospective data collection.