Funding for this research was provided by:
Helse Sør-Øst RHF (2004-259 and 2006-186)
Text and Data Mining valid from 2020-03-04
Received: 25 June 2019
Accepted: 26 February 2020
First Online: 4 March 2020
Ethics approval and consent to participate
: This study was approved by the Regional Committee for Medical Research Ethics and the Norwegian Data Inspectorate. Registration numbers: 2004/39–05-04248 and 593–04248, and 2013/1145/REK sør-øst. All participants (and legal parents when the participants were below 16 years) gave their written informed consent prior to their inclusion in the study. The authors confirm that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008.
: Not applicable.
: The authors declare that they have no competing interests.