Text and Data Mining valid from 2019-08-14
Received: 2 April 2019
Accepted: 19 July 2019
First Online: 14 August 2019
Ethics approval and consent to participate
: The study was approved by the local ethics committee Kanton Zurich and written informed consent was waived by the local ethics comitee (KEK StV. 25–2008).
: Not applicable
: The authors declare that they have no competing interests.