Funding for this research was provided by:
Bundesministerium für Bildung und Forschung (01KR1203A)
Received: 2 January 2019
Accepted: 7 May 2019
First Online: 29 May 2019
Ethics approval and consent to participate
: The ethics committee of the Hamburg State Medical Chamber approved the conduct of this study.
: Not applicable.
: The authors declare that they have no competing interests.
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