1. Erasmus Medical Center; Department of General Practice; PO Box 2040 Rotterdam Netherlands 3000 CA
2. VU University Medical Center; Department of General Practice and Elderly Care Medicine, Amsterdam Public Health Research Institute; PO Box 7057 Amsterdam Netherlands 1007 MB
3. Erasmus Medical Center - Sophia Children's Hospital; Department of Paediatrics, Paediatric Rheumatology; PO Box 2060 Rotterdam Netherlands 3000 CB