1. Department of Cardiology; University Medical Centre Groningen, University of Groningen; PO Box 30.001 9700 RB Groningen The Netherlands
2. Department of Epidemiology; University Medical Centre Groningen, University of Groningen; Groningen The Netherlands
3. College of Nursing; University of Kentucky; Lexington KY USA
4. Health Psychology Section, Department of Health Science; University Medical Centre Groningen, University of Groningen; Groningen The Netherlands