Funding for this research was provided by:
EuroQol Research Foundation (20180330)
Received: 20 February 2020
Accepted: 7 May 2020
First Online: 19 May 2020
Ethics approval and consent to participate
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the ethics committee (Toetsingscommissie Wetenschappelijk Onderzoek Rotterdam, registration number NL59981) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Written informed consent was obtained from all individual participants included in the study.
: Not applicable.
: The authors declare that they have no competing interests.