Text and Data Mining valid from 2019-11-15
Received: 17 April 2019
Accepted: 23 October 2019
First Online: 15 November 2019
Compliance with ethical guidelines
: S. Gerum, C. Heinz, C. Belka, F. Walter, P.M. Paprottka, E.N. De Toni, and F. Röder declare that they have no competing interests.
: The study was approved by the Ethics committee of the University of Munich (LMU), reference number 617-16. Informed consent was obtained from all individual participants included in the study.