Epidemiology
A recent analysis of data from the 2003–2004 US National Health and Nutrition Examination Survey (NHANES) showed psoriasis to have an estimated prevalence of 3.15%, which corresponds to approximately 5 million American adults.1 The rate of undiagnosed but active psoriasis was estimated in the range of 0.4% to 2.28%.1 In this US survey, psoriasis tended to be undiagnosed among patients who were male, non-white, unmarried and less educated.1 Among those with a diagnosis, 17% had moderate to severe symptoms.1
Psoriasis can present at any age, but initial clinical signs and symptoms are usually detected between 10 and 30 years of age.3 Two types of psoriasis have been proposed based on age of onset and association with human leukocyte antigen (HLA): Type I psoriasis is early onset (<40 years of age) and associated with the HLA-Cw6 allele, and involves a greater percentage of body surface area. Type II psoriasis has a later onset (>40 years), occurs sporadically around the body surface and is not associated with any HLA marker.3 However, many patients do not neatly fit into these broad categories.
Psoriasis occurs at a similar rate in men and women.1 African Americans appear to be at a lower risk for developing psoriasis compared with Caucasians (prevalence 1.3% and 2.5%, respectively), but those who are affected experience similar quality-of-life issues and similar levels of satisfaction with treatment.4 The prevalence of psoriasis among Hispanic Americans also appears to be far lower than among white Americans.1
- Kurd SK, Gelfand JM. The prevalence of previously diagnosed and undiagnosed psoriasis in US adults: results from NHANES 2003-2004. J Am Acad Dermatol. 2009;60(2):218-224
- Elder JT, Bruce AT, Gudjonsson JE, et al. Molecular dissection of psoriasis: integrating genetics and biology. J Invest Dermatol. 2010;130(5):1213-1226.
- Henseler T, Christophers E. Psoriasis of early and late onset: characterization of two types of psoriasis vulgaris. J Am Acad Dermatol. 1985;13(3):450-456.
- Gelfand JM, Stern RS, Nijsten T, et al. The prevalence of psoriasis in African Americans: results from a population-based study. J Am Acad Dermatol. 2005;52(1):23-26.
