Text and Data Mining valid from 2019-09-04
Received: 25 June 2019
Accepted: 29 August 2019
First Online: 4 September 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest
: The present study was approved by the local ethics committee af the University of Bonn.
: Informed consent was not sought as a retrospective design was used.