1 European Network for Children with Arthritis, MCI Secretariat, Geneva, Switzerland.
2 Department of Paediatric Rheumatology, University Medical Center Utrecht, Utrecht 3508AB, Netherlands; Council of Pediatric Rheumatology European Society, Geneva, Switzerland.
3 Council of Pediatric Rheumatology European Society, Geneva, Switzerland; Department of Pediatric Rheumatology, University of Liverpool, Alder Hey Children's Hospital, Liverpool, UK.
4 Department of Paediatric Rheumatology, University Medical Center Utrecht, Utrecht 3508AB, Netherlands. Electronic address: n.wulffraat@umcutrecht.nl.