Text and Data Mining valid from 2019-02-15
Received: 16 July 2018
Accepted: 7 February 2019
First Online: 15 February 2019
Ethics approval and consent to participate
: Informed consent was obtained from both the parents and the children prior to the study. The National Committees for Medical and Health Research Ethics (REK) (file number S-01076) in Norway gave ethical approval and research clearance for the initial study (baseline and first and second follow-up). The subsequent surveys were approved by The Norwegian Centre for Research Data (NSD) (file number 12395).
: Not applicable.
: The authors declare that they have no competing interests.
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