LAUSR

Background Psoriasis is an immune-mediated chronic inflammatory disease that affects the skin and/or joints of a person. Although the exact cause of psoriasis has not been determined, it is thought to be caused by a combination of genetic and environmental factors. Environmental factors, including stress, injury and infections, trigger an inflammatory immune response involving dendritic cells, T cells, keratinocytes, neutrophils and cytokines in those predisposed to thedisease. Theprevalenceof thedisease ranges from 0.91% in the United States to 8.5% inNorway. There are several types of psoriasis, including plaque, pustular, inverse and erythrodermic, with plaque psoriasis the most common, affecting 90% of sufferers. The signs and symptoms of this type of psoriasis include raised erythematous and well-demarked areas of inflamed skin, covered by silvery white, scaly skin, typically located on the elbows, knees, scalp, lower back and periumbilical region. The severity of symptoms varies, ranging from exacerbations of the disease that can involve the whole body, to minor localized patches of inflammation and remission. A psychological impact has also been reported, with impairment of quality of life and stigma associated with symptomology. No cure exists for psoriasis and treatment involves symptommanagement. Treatment regimes are, typically long term in nature and involve two discrete phases: induction therapy, leading to short-term remission and maintenance therapy, leading to long-term remission. Topical agents are the first line of treatment; however in moderate-to-severe cases a second-line therapy may be required, for example phototherapy and the use of conventional systemic agents such as cyclosporine or methotrexate. Progress in physiological comprehension led to the emergence of biologic treatments and offered new therapeutic possibilities for patients. Biologic treatments work by suppressing the immune system.