1. Cochrane Skin Group; University of Nottingham; Nottingham U.K.
2. Centre for Research in Environmental Epidemiology (CREAL); Barcelona Spain
3. Hospital del Mar Research Institute (IMIM); Barcelona Spain
4. CIBER Epidemiología y Salud Pública (CIBERESP); Barcelona Spain
5. Department of Experimental and Health Sciences; University of Pompeu Fabra (UPF); Barcelona Spain
6. Centre of Evidence Based Dermatology; University of Nottingham; Nottingham U.K.
7. Division of Epidemiology and Public Health; University of Nottingham; Nottingham U.K.
8. Unit of Dermatology; CLÍNICA GO&FER; Barcelona Spain
9. Department of Dermatology; St George's Hospital; London U.K.
10. Department of Dermatology; AP-HP; Hôpital Henri Mondor; Créteil France
11. EA EpiDermE (Epidémiologie en Dermatologie et Evaluation des Thérapeutiques); UPEC; Créteil France
12. Université Paris-Est Créteil; Créteil France