Malmborg, Morten https://orcid.org/0000-0002-9867-3283
Christiansen, Christine Benn
Schmiegelow, Michelle D.
Torp-Pedersen, Christian
Gislason, Gunnar
Schou, Morten
Article History
Received: 10 January 2018
Accepted: 8 October 2018
First Online: 22 October 2018
Ethics approval and consent to participate
: Retrospective register studies do not need ethical approval in Denmark. The Danish Data Protection Agency has approved the project (reference number 2007–58-015/GEH 2014–014, I-Suite no: 02732).
: Not applicable.
: The authors declare that they have no competing interests.
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