Text and Data Mining valid from 2019-03-27
Received: 19 November 2018
Accepted: 22 March 2019
First Online: 27 March 2019
Ethics approval and consent to participate
: The study was approved by the Norwegian Centre for Research data – NSD (project no. 51795, 2017). All participants signed a written form of consent after having received oral and written information about the study.
: Not applicable.
: The authors declare that they have no competing interests.
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