1. Department of Health Psychology, Utrecht University, Heidelberglaan 1, P.O. Box 80.140, 3508 TC Utrecht, The Netherlands
2. Department of Methodology and Statistics, Utrecht University, The Netherlands
3. Center of Research on Psychology in Somatic disease (CoRPS), Department of Psychology and Health Tilburg University, The Netherlands
4. Department of Rheumatology and Clinical Immunology, University Medical Center Utrecht, The Netherlands