Received: 3 October 2021
Accepted: 25 February 2022
First Online: 12 March 2022
: In Denmark, no ethical approval is required for retrospective registry studies. The ethics review board at Maastricht University approved the study in March 2020, with no further ethical reservations. Further, the standards of ethical conduct outlined by the Netherlands Code of Conduct for Research Integrity were followed. The ethical clearance number is FMHL/BEPH/2020.016.
: The authors declare no conflict of interest.