Funding for this research was provided by:
University of Innsbruck and Medical University of Innsbruck
Received: 8 September 2017
Accepted: 29 March 2018
First Online: 17 April 2018
Conflict of interest
: G. Ruedl, D. Franz, A. Frühauf, M. Kopp, M. Niedermeier, C. Drenowatz, and K. Greier declare that they have no competing interests.