Text and Data Mining valid from 2020-01-23
Received: 15 August 2019
Accepted: 17 January 2020
First Online: 23 January 2020
Ethics approval and consent to participate
: The study was approved by the local ethics committee (Zurich Cantonal Ethics Commission, Req-2019-00133). Written informed consent was obtained from all individual participants included in the study.
: Not applicable.
: The authors declare that they have no competing interests.