1 Dudley Group NHS Foundation Trust, UK; Arthritis Research UK Centre for Epidemiology, University of Manchester, UK. Electronic address: Kitas@dgh.nhs.uk.
2 Scientific Institute for Quality of Healthcare, Radboud University Medical Center, Nijmegen, The Netherlands; Department of Rheumatology, Bernhoven, Uden, The Netherlands. Electronic address: Piet.vanriel@radboudumc.nl.