Text and Data Mining valid from 2019-08-27
Received: 6 May 2019
Accepted: 15 July 2019
First Online: 27 August 2019
Ethics approval and consent to participate
: The protocol of this retrospective study was approved by the local ethics committee of the University of Luebeck (# 19-075A).
: Not applicable
: The authors declare that they have no competing interests