1. University Medical Center Utrecht; Julius Center; Universiteitsweg 100 Utrecht Netherlands 3584 CG
2. University Medical Center Utrecht; Julius Center for Health Sciences and Primary Care; PO Box 85500 Utrecht Netherlands 3508 AB
3. Institute of General Practice, Medical Faculty of the Heinrich-Heine-University Düsseldorf; Cochrane Metabolic and Endocrine Disorders Group; Moorenstr. 5 Düsseldorf Germany 40225