Received: 6 July 2018
Accepted: 8 October 2018
First Online: 16 November 2018
Ethics approval and consent to participate
: The study was approved by the cantonal ethics committee of the canton of Zurich (KEK 2016-00070).
: Not applicable
: Josipa Radic, Raphael Patcas, Bernd Stadlinger, Daniel Wiedemeier, Martin Rücker and Barbara Giacomelli-Hiestand declare that they have no competing interests.
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