Funding for this research was provided by:
University of Iceland Research Fund (N/A)
Received: 4 December 2020
Accepted: 5 July 2021
First Online: 18 July 2021
: The study complies with the Declaration of Helsinki and it was based on register-data from two different data holders, the Icelandic Health Insurances and Statistics Iceland. Each data holder approved the use of data for the study. The study design, including information on register-data sources and data holders were presented in a research protocol which was thoroughly assessed and approved by the Icelandic National Bioethics Committee (VSNb2015100032/03.03). The Committee waived requirements for informed consent from each subject; based on Icelandic regulations on retrospective, register-based studies and careful data-protection processes followed by data holders. The Icelandic Health Insurances protected the identity of individuals in their database by replacing personal identification number with an anonymous research number. The researchers did not have access to the subjects’ personal identification numbers. Data on the general Icelandic population are based on anonymous public register information from Statistics Iceland.
: Not applicable.