Psoriasis is the most common autoimmune disease in the United States. It is a relapsing and remitting immune-mediated inflammatory disease that affects the skin and joints. Plaque psoriasis, a chronic inflammatory skin disease, accounts for 80-90% of all psoriasis patients and appears as raised, red patches covered with a silvery white buildup of dead skin cells, typically found at the elbows, knees, scalp and genital area. Psoriasis is associated with comorbid conditions, including depression, arthritis, diabetes, hypertension, metabolic syndrome and cardiovascular events, and has a major impact on health-related quality of life, affecting daily activities of 60% of patients with moderate-to-severe psoriasis.

It is estimated that psoriasis affects 2% of the population worldwide, including approximately 6 million people in the United States, and that 20-30% of psoriasis patients have moderate-to-severe psoriasis. Although psoriasis can affect all age groups, the onset of psoriasis tends to peak between the ages of 20 and 30 and between ages 50 and 60.