Funding for this research was provided by:
Received: 23 August 2019
Accepted: 3 January 2020
First Online: 10 January 2020
Ethics approval and consent to participate
: Ethical approval is not required due to the register-based nature of the study. This is based on the Act on Research Ethics Review of Health Research Projects, section 14, [CitationRef removed] “Notification of questionnaire surveys and medical database research projects to the system of research ethics committee system is only required if the project involves human biological material” (ExternalRef removed). The study was approved by the Danish Data Protection Agency.
: Not applicable.
: The authors declare that they have no competing interests