1. Department of Internal Medicine, Subdivision of Rheumatology, Maastricht University Medical Center, 6202 AZ Maastricht, The Netherlands, and Biomedical Research Institute, University Hasselt, Belgium,
2. Department of General Practice, Maastricht University, Maastricht, The Netherlands
3. Department of Internal Medicine, Maastricht University Medical Center, Maastricht, The Netherlands and Viecuri Medical Center Noord Limburg, Venlo, The Netherlands