Text and Data Mining valid from 2020-05-04
Received: 28 November 2019
Accepted: 31 March 2020
First Online: 4 May 2020
Ethics approval and consent to participate
: Ethics approval was granted by the Regional Committee for Medical Research ethics, South East Norway [REK2014/2223]. All participants gave their written consent to participate.
: Not applicable.
: The authors declare that they have no competing interests.