Text and Data Mining valid from 2019-12-01
Received: 12 November 2017
Accepted: 10 December 2019
First Online: 19 December 2019
Ethics approval and consent to participate
: The regional institutional review board (Kantonale Ethikkommision Zürich, Switzerland, StV-01/2008, 20.11.2007) approved this study. The need for consent from patients was waived because the database was an anonymous registry.
: Not applicable.
: The authors declare that they have no competing interests.