1. St John's Institute of Dermatology; Guy's and St Thomas' NHS Foundation Trust; London SE1 9RT U.K
2. Division of Health and Social Care Research; Guy's and St Thomas' NHS Foundation Trust; London SE1 9RT U.K
3. Department of Dermatology; CHU Hôtel-Dieu; 44035 Nantes France
4. Pediatric Dermatology Unit; Department of Dermatology; Hospital de la Santa Creu i Sant Pau; Barcelona Spain
5. Department of Dermatology; Aarhus University Hospital; Aarhus Denmark
6. Department of Dermatology; University Hospital Schleswig-Holstein; Kiel Germany
7. Department of Pathophysiology and Transplantation; University of Milan and Fondazione IRCCS Ca' Granda; Ospedale Maggiore Policlinico; Milan Italy
8. Hospital Infantil Niño Jesús; Madrid Spain
9. Department of Dermatology; Academic Medical Center; Amsterdam the Netherlands
10. Department of Dermatology; Maasstadziekenhuis; Rotterdam the Netherlands
11. Division of Asthma, Allergy and Lung Biology; Department of Paediatric Allergy; King's College London; London U.K
12. Dermatology, Department of Specialised, Experimental and Diagnostic Medicine; University of Bologna; Bologna Italy
13. Department of Dermatology; Royal Infirmary of Edinburgh; Edinburgh U.K
14. Department of Dermatology; Institute of Clinical Research in Malmö; Skåne University Hospital; Lund University; Malmö Sweden
15. Dermatology Unit; Department of Medicine Solna; Karolinska Institutet; Stockholm Sweden
16. Centre for Evidence-Based Healthcare; University of Dresden; Dresden Germany
17. Department of Social and Occupational Medicine; University of Dresden; Dresden Germany