1. University Medical Center Utrecht; Department of Otorhinolaryngology - Head and Neck Surgery; G05.129; Heidelberglaan 100 Utrecht Netherlands 3584 CX
2. Faculty of Medicine Universitas Indonesia - Cipto Mangunkusumo Hospital; Centre for Clinical Epidemiology & Evidence-Based Medicine; Jakarta Indonesia
3. VU University; Department of Health Sciences, Faculty of Earth and Life Sciences; PO Box 7057 Room U454 Amsterdam Netherlands 1007 MB
4. Department of Public Health and Caring Sciences; Family Medicine Section; Uppsala Science Park Uppsala Sweden SE-751 85
5. VU University Medical Center; Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research; PO Box 7057 Amsterdam Netherlands 1007 MB
6. Northwestern Health Sciences University; Wolfe-Harris Center for Clinical Studies; 2501 West 84th Street Bloomington MN USA 55431
7. VU University; De Boelelaan 1105 Amsterdam Netherlands 1081 HV
8. Academic Center for Dentistry Amsterdam (ACTA); Department of Social Dentistry; 5th Floor, Room 5N03 Gustav Mahlerlaan 3004 Amsterdam Netherlands 1081LA