Received: 30 October 2017
Accepted: 26 July 2018
First Online: 7 August 2018
Ethics approval and consent to participate
: The study was approved by the ethical commission in Geneva (CCER - 14-235). All participants signed the written informed consent after having received information about the study and time to decide about participation.
: Not applicable – but consent was obtained from all included subjects.
: The authors declare that they have no competing interests.
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