Funding for this research was provided by:
Received: 15 August 2018
Accepted: 14 November 2018
First Online: 6 December 2018
Ethics approval and consent to participate
: This study was approved by the ethics committee of the University of Ulm on the 4th of August 2017 (covering the study sites: Ravensburg, Ulm, Neuruppin) According to state regulations of Lower Saxonia, a separate ethics approval was needed for the study site Lueneburg, which was obtained on the 25th of October 2017 by the Ethicscommittee of Lower Saxonia. Written informed consent will be obtained from each participant before inclusion in the study.
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.