Received: 23 January 2020
Accepted: 23 April 2020
First Online: 1 June 2020
Ethics approval and consent to participate
: The study was approved by the Regional Committee for Medical Research Ethics, South-East Norway (REK2014/2223). All participants provided written informed consent and, for former patients under 16 years old, parental consent.
: Not applicable.
: The authors have no competing interests.