Funding for this research was provided by:
Helse Nord RHF (HNF1383-17)
Received: 11 February 2020
Accepted: 6 August 2020
First Online: 20 August 2020
Ethics approval and consent to participate
: The study was performed in compliance with the Helsinki Declaration for research on humans and was approved by the Regional Committees for Medical and Health Research Ethics (REC North). Reference number 2011/1937. All participants participated and consented according to the regulations in the research project, also with written parental consent for those under age 16 (REC North, Reference number 2011/1937).
: Consent to publish was given from every participant and parents when warranted according with the Helsinki Declaration for research on humans and was approved by the REC North (Reference number 2011/1937).
: The authors declare that they have no conflicts of interest.