1. Department of Dermatology; Leeds Teaching Hospitals NHS Trust; Leeds LS7 4SA UK
2. Clinica Dermatologica, Department of Health Sciences (DiSSAL); Università di Genova, Ospedale Policlinico San Martino; 16132 Genoa Italy
3. Contact Allergy Unit, Department of Dermatology; University Hospital KU Leuven; 3000 Leuven Belgium
4. Department of Dermato-Allergology, National Allergy Research Centre; Gentofte Hospital, University of Copenhagen; 2900 Hellerup Denmark
5. Department of Dermatology; Free University of Amsterdam; 1081 HV Amsterdam The Netherlands
6. Department of Dermatology; Hospital de La Princesa; 28006 Madrid Spain
7. Department of Dermatology; University Medical Centre Groningen, University of Groningen; 9713 GZ Groningen The Netherlands
8. Department of Medical Informatics; Biometry and Epidemiology, University of Erlangen/Nürnberg; 91054 Erlangen Germany