Received: 4 January 2021
Accepted: 25 January 2021
First Online: 18 February 2021
Ethics approval and consent to participate
: Written informed consent was obtained from adolescents and parents participating at T<sub>1</sub> and T<sub>2</sub>, according to study procedures. Study approval was given by the Regional Committee for Medical and Health Research Ethics of Central Norway (REK Midt) (reference numbers CAP survey T<sub>1</sub>: 4.2008.1393, T<sub>2</sub>: 2011/1435/REK Midt, and present study using T<sub>1</sub> and T<sub>2</sub> data: 2017/589/REK Midt). The Norwegian Social Science Data Services, The Data Protection Official for Research, gave permission to compare the main reason for referral, age and sex between participants and non-participants at baseline (reference number CAP survey: 19976). The research followed the agreement of the ethical standards in the Declaration of Helsinki from 1964 and later amendments, and we confirm that all methods were performed in accordance with relevant guidelines and regulations.
: Not applicable.
: The authors declare that they have no competing interest.