Funding for this research was provided by:
German Medical Association Bundesärztekammer (06-115)
Received: 26 October 2017
Accepted: 23 April 2018
First Online: 2 May 2018
Ethics approval and consent to participate
: The study was approved by the ethics committee of the Medical Faculty of the Heinrich-Heine University Düsseldorf. All participants provided written informed consent.
: The authors declare that they have no competing interests.
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