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Article History

Received: 31 January 2017

Accepted: 15 November 2018

First Online: 6 December 2018

Ethics approval and consent to participate

: Danish legislation does not require ethical approval for register studies according to “Guidelines about Notification etc. of a Biomedical Research Project” Law no. 593, 14 June 2011 []. Section 2.7 states, “<i>A register research project where only information in the form of sign-based symbols, including figures, letters, etc. is applied shall not be notified to research ethics committees.</i>” [].The study was approved by the Danish Data Protection Agency (j.nr. 2014-41-2928) and The Danish Health and Medicines Authority j.nr. 3–3013-582/1/.Approval for the study was also granted by the relevant authorities at the hospital.

: Not applicable.

: The authors declare that they have no competing interests.

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