Funding for this research was provided by:
The TRYG Foundation
Research Council of Norway (249932/F20)
Received: 7 July 2020
Accepted: 30 August 2020
First Online: 7 September 2020
Ethics approval and consent to participate
: Participants provided written informed consent from a parent or legal guardian. The CHAMPS-study DK was approved by the ethnical committee, Region of Southern Denmark (ID S-20080047) and registered at the Danish Data Protection Agency (J.nr. 2008-41-2240).
: Not applicable.
: All authors declare that they have no competing interests.