1. Department of Dermatology; Helsingborg Hospital; Department of Clinical Sciences Lund; Faculty of Medicine; Lund University; S Vallgatan 5 Helsingborg S-251 87 Sweden
2. Department of Dermatology and Venereology; Medical University of Graz; Graz Austria
3. Research and Development Centre; Skåne; Unit for Medical Statistics and Epidemiology; Skåne University Hospital; Lund Sweden