1. Department of Dermatology; University of Utah; 4A330 School of Medicine; 30 North 1900 East Salt Lake City UT 84132 U.S.A
2. Department of Internal Medicine; Yale University School of Medicine; 333 Cedar Street New Haven CT 06510 U.S.A
3. Department of Dermatology; University of Pennsylvania; Perelman School of Medicine; 14 Penn Tower, 1 Convention Avenue Philadelphia PA 19104 U.S.A
4. Center for Clinical Epidemiology and Biostatistics; University of Pennsylvania; Perelman School of Medicine; Philadelphia PA U.S.A
5. National Psoriasis Foundation; 6600 SW 92nd Ave, Suite 300 Portland OR 97223 U.S.A
6. Department of Biostatistics and Epidemiology; Blockely Hall, 423 Gaurdian Drive Philadelphia PA 19104 U.S.A