Funding for this research was provided by:
Danish Medical Research Council (09-060078/FSS)
The Danish Ministry of Health (2003-0200-13)
Aase og Ejnar Danielsens Fond
Received: 8 March 2019
Accepted: 27 August 2019
First Online: 10 September 2019
Ethics approval and consent to participate
: The YSS study was conducted in accordance with the Helsinki Declaration. According to Danish legislation, there was no request for ethical approval, nor was there a consent procedure for minors when baseline data was collected. However, at the follow-up study in 2005, all participants provided written informed consent and approval was obtained from the Danish Data Protection Agency (Journal number: 2015-41-3940), as well as the local ethical committee (The scientific ethical committee for Copenhagen and Frederiksberg [KF 01–260/04]).
: Not applicable.
: The authors declare that they have no competing interests.