Received: 4 June 2018
Accepted: 2 November 2018
First Online: 16 November 2018
Ethics approval and consent to participate
: The study was approved by the local ethics committee of the medical faculty at RWTH Aachen University (No. EK- 100/12). All participants and raters provided written consent to contribute to this study.
: Not applicable.
: The authors declare that they have no competing interests.
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