Funding for this research was provided by:
research funds division of rheumatology, university hospital bern (not applicable)
Received: 17 September 2019
Accepted: 5 March 2020
First Online: 24 March 2020
Ethics approval and consent to participate
: As a rule of EUSTAR, each participating center is obliged to obtain ethics approval by their respective local ethics committee prior to data acquisition and transmission.
: Not applicable
: The authors declare that they have no competing interests.