Funding for this research was provided by:
Norges Forskningsråd (214298)
Received: 11 March 2019
Accepted: 1 May 2020
First Online: 24 May 2020
Ethics approval and consent to participate
: The study was approved by The Regional Committee for Medical and Health Research Ethics for central Norway (approval number 2012/852) and the Norwegian Social Science Data Services (the Privacy Ombudsman for Research). Consent to participate could not be obtained as our study involved a decedent population.
: Not applicable.
: The authors declare that they have no competing interests.