Psoriasis is a chronic inflammatory disease which affects approximately 2% of the population, and in the majority of cases presents with disfiguring, scaling and erythematous plaques of the skin.
This section of the Psoriasis Learning Zone will provide an overview of the disease, including epidemiology, the link with psoriatic arthritis, the burden of disease and the role of cytokines in psoriasis development.
Psoriasis is a widespread and complex disorder that results from an interplay between multiple genetic and environmental factors (Parisi et al., 2013; Griffiths & Barker, 2007).
Psoriasis has a wide range of clinical manifestations and although worldwide incidence and prevalence is poorly understood, psoriasis is estimated to affect around 2–4% of the population in Western countries (Parisi et al., 2013).
Psoriatic arthritis (PsA) occurs in around 20% of psoriasis patients as a systemic, polymorphic disease of the joints that varies in presentation and clinical course. (Zachariae et al., 2003; Goldenstein-Schainberg et al., 2012; Alinaghi et al., 2018). Skin involvement is not required to establish the diagnosis.
PsA is diagnosed based on specific joint symptoms (such as enthesitis, present in 60–80%, and dactylitis, present in 30%) and serology (usually negative for rheumatoid factor and cyclic citrullinated peptide) (Coates & Helliwell, 2017).
Burden of disease
Psoriasis continues to have a significant impact on quality of life, health-care resource utilisation, costs and productivity. A US study suggested that despite treatment, many psoriasis patients continue to experience clinical symptoms and impaired functioning (Schaefer et al., 2015).
Psoriasis is more than a dermatological disorder. It is a chronic immune-mediated disease in which genetically susceptible individuals develop cutaneous inflammation and keratinocyte hyperproliferation (Nestle et al., 2009; Boehncke & Schön, 2015).
Psoriasis is associated with epidermal thickening and keratinocyte hyperproliferation. As a result, the skin becomes inflamed and has raised plaques with silvery scales (as shown in the figure below), which can cover large areas of the body (Nestle et al., 2009; Boehncke & Schön, 2015; Palfreeman et al., 2013).
Psoriasis disease awareness references
References used throughout the disease awareness section of the Psoriasis Learning Zone.
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