MedWire News: Up to 5% of the US population may have psoriasis, with up to two-thirds of these cases being undiagnosed, say researchers.

“Our results suggest that a large number of patients with active psoriasis remain undiagnosed and that a variety of socioeconomic disparities may explain why psoriasis may be undiagnosed,” say Shanu Kurd and Joel Gelfand from the University of Pennsylvania School of Medicine in Philadelphia, USA.

The researchers analyzed data on 2984 adults, aged 20–59 years, who participated in the US National Health and Nutrition Examination Survey for 2003–2004. Of these, 3.15% reported having received a diagnosis of psoriasis. This corresponds to about 5 million adults in the US population.

About 17% of these patients had moderate-to-severe psoriasis, defined as psoriasis affecting at least 3% of body surface area. A quarter of the psoriasis patients said their condition was a large problem in their everyday lives.

When two dermatologists reviewed standardized clinical photographs of the participants, both agreed that a further 0.4% of participants had psoriasis, and at least one dermatologist diagnosed psoriasis in 2.28% of patients with no previous diagnosis. These rates correspond to 600,000 and 3.6 million US adults, respectively.

Based on the less conservative estimate, which gave a larger sample size, patients with undiagnosed psoriasis were more likely than those with diagnosed psoriasis to be male, non-White and unmarried, and they had lower household incomes and were less educated.

“Additional studies are needed to better define the prevalence of undiagnosed psoriasis and to determine what barriers exist which prevent these patients from receiving medical care for this important disease,” the researchers conclude in the Journal of the American Academy of Dermatology.

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