1 Department of Dermatology, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland.
2 Department of Dermatology, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland; Centro Studi, The Italian Group for Epidemiological Research in Dermatology (GISED), Bergamo, Italy.
3 Department of Dermatology, Inselspital Bern University Hospital, University of Bern, Bern, Switzerland. Electronic address: laurence.feldmeyer@insel.ch.