Funding for this research was provided by:
Received: 20 July 2018
Accepted: 27 May 2019
First Online: 1 June 2019
Ethics approval and consent to participate
: The study was approved by the Danish Data Protection Agency (2015-57-0002) and data were handled confidentially in strict accordance with the guidelines. According to the Consolidation Act on Research Ethics Review of Health Research Projects, Consolidation Act number 1083 of 15 September 2017, section 14(2) notification of questionnaire surveys or medical database research projects to the research ethics committee system is only required if the project involves human biological material.
: Not applicable.
: The authors declare that they have no competing interests.