[1] Univ Penn, Perelman Sch Med, Dept Dermatol, Philadelphia, PA 19104 USA
[2] Univ Penn, Ctr Clin Epidemiol & Biostat, Perelman Sch Med, Dept Epidemiol & Biostat, Philadelphia, PA 19104 USA
[3] Univ Penn, Perelman Sch Med, Div Rheumatol, Philadelphia, PA 19104 USA
[4] London Sch Hyg & Trop Med, London, England
[5] St Johns Inst Dermatol, London, England
[6] NHLBI, Bldg 10, Bethesda, MD 20892 USA
[7] Eastern Virginia Med Sch, Dept Dermatol, Norfolk, VA 23501 USA