Article History
Received: 5 September 2016
Accepted: 4 November 2016
First Online: 1 December 2016
Compliance with ethical guidelines
:
: M. Holschen, F. Brand, and J.D. Agneskirchner declare that they have no competing interests.
: Ethical approval was given from the ethics committee of the medical faculty of the University of Hannover, Germany.