Received: 12 April 2018
Accepted: 13 June 2018
First Online: 13 July 2018
Ethics approval and consent to participate
: The study was approved by the Danish Data Protection Agency (2016–051-000001, ID:665). In agreement with the rules of the Danish Health Authorities, informed and signed consent was provided by all participants ≥15 years of age, and by their parents for participants below age 15.
: Signed consent was granted by participants ≥15 years of age or by their parents for participants below age 15.
: The authors declare that they have no competing interests.
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