Funding for this research was provided by:
Helse Nord RHF
Text and Data Mining valid from 2019-12-01
Received: 25 July 2019
Accepted: 8 November 2019
First Online: 5 December 2019
Ethics approval and consent to participate
: Approval from medical research ethical committees and data protection authorities was granted according to the regulations of each participating country; in Norway, this was from the Regional Committee for Medical and Health Research Ethics NORD, number 53/96. Oral informed assent was obtained from all children. Written informed consent was obtained from parents of children aged < 16 years and from the children if aged ≥ 16 years of age.
: Not applicable.
: The authors declare that they have no competing interests.