Received: 17 February 2018
Accepted: 16 August 2018
First Online: 23 August 2018
Ethics approval and consent to participate
: Informed consent was obtained from all participants. Approval for the study and the way of obtaining consent was granted by the Ethics Committee of the Medical Faculty of the University of Erlangen (Registration Number 227_14B).
: Not applicable.
: The authors declare that they have no competing interests.
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