Psoriasis Facts

Q: How many people in the United States have psoriasis? In what patient population is it most prevalent?
A: Approximately 7.5 million people in the United States have psoriasis.1 Psoriasis occurs in all age groups but is primarily seen in adults. Up to 40% of people with psoriasis experience joint inflammation that produces symptoms of arthritis, according to the American Academy of Dermatology. This condition is psoriatic arthritis. Psoriatic arthritis patients also experience other arthritis symptoms.2,3

Q: What are other types of psoriasis?
A: Other forms of psoriasis include inverse, erythrodermic, pustular, guttate, and nail disease.1 In 2013, the total direct cost of treatment associated with psoriasis was estimated between $51.7 billion and $63.2 billion.4

Q: What is the most common form of psoriasis?
A: Plaque psoriasis is the most common form of psoriasis, affecting about 80% to 90% of people with psoriasis. It is characterized by patches of raised, reddish skin covered with silvery-white scale.1

Q: What parts of the body are affected by psoriasis?
A: Psoriasis usually occurs on the scalp, knees, elbows, hands, and feet. Approximately 80% of those affected with psoriasis have mild to moderate disease, while 20% have moderate to severe psoriasis affecting more than 5% of the body surface area.1

Q: Are there specific triggers for psoriasis?
A: Psoriasis triggers are not universal. What may cause one person’s psoriasis to become active, may not affect another, according to the National Psoriasis Foundation. Established psoriasis triggers include stress, injury to skin (Koebner phenomenon), medications (lithium, antimalarials, inderal, quinidine, and indomethacin), and infection.5

Q: What are some of the common comorbidities of psoriasis?
A: People with psoriasis or psoriatic arthritis are at a higher risk for developing other chronic comorbidities. The incidence of Crohn disease and ulcerative colitis is 3.8 to 7.5 times greater in psoriasis individuals than in the general population.6 Individuals with psoriasis also have an increased incidence of lymphoma,7,8 heart disease,9,10 obesity,11,12 type 2 diabetes,13 and metabolic syndrome.14 Depression and suicide,15 smoking,16 and alcohol consumption17 are also more common in individuals with psoriasis. In addition, psoriasis can have a substantial psychological and emotional impact on people living with the skin disease. For example, the prevalence of depression in individuals with psoriasis may be as high as 50%. They also experience physical and mental disability just like people with other chronic illnesses such as cancer, arthritis, hypertension, heart disease, and diabetes.18

Q: Are there specific genes that make a person more likely to develop psoriasis?
A: Scientists have now identified about 25 genetic variants that make a person more likely to develop psoriatic disease. For example, working with DNA samples from a large family that includes many people with psoriasis, Anne Bowcock, PhD, professor of genetics, Washington University School of Medicine, St. Louis, MO, has identified a gene mutation known as CARD14 that when triggered leads to plaque psoriasis. The DNA samples came from the National Psoriasis Victor Henschel BioBank.5


1. Menter A, Gottlieb A, Feldman SR, et al. Guidelines of care for the management of psoriasis and psoriatic arthritis: Section 1. Overview of psoriasis and guidelines of care for the treatment of psoriasis with biologics. J Am Acad Dermatol. 2008;58(5):826-850.
2. Questions and answers about psoriasis. National Institutes of Arthritis and Musculoskeletal and Skin Diseases website. Accessed June 22, 2016.
3. About psoriasis. National Psoriasis Foundation website. Accessed June 22, 2016.
4. Brezinski EA, Dhillon JS, Armstrong AW. Economic burden of psoriasis in the United States: a systematic review. JAMA Dermatol. 2015;151(6):651-658.
5. Psoriasis causes and triggers. National Psoriasis Foundation website. Accessed June 22, 2016.
6. Najarian DJ, Gottlieb AB. Connections between psoriasis and Crohn’s disease. J Am Acad Dermatol. 2003;48(6):805-821; quiz 822-824.
7. Gelfand JM, Shin DB, Neimann AL, Wang X, Margolis DJ, Troxel AB. The risk of lymphoma in patients with psoriasis. J Invest Dermatol. 2006;126(10):2194-2201.
8. Gelfand JM, Berlin J, Van Voorhees A, Margolis DJ. Lymphoma rates are low but increased in patients with psoriasis: results from a population-based cohort study in the United Kingdom. Arch Dermatol. 2003;139(11):1425-1429.
9. Gelfand JM, Neimann AL, Shin DB, Wang X, Margolis DJ, Troxel AB. Risk of myocardial infarction in patients with psoriasis. JAMA. 2006;296(14):1735-1741.
10. Neimann AL, Shin DB, Wang X, Margolis DJ, Gelfand JM, Troxel AB. Prevalence of cardiovascular risk factors in patients with psoriasis. J Am Acad Dermatol. 2006;55(5):829-835.
11. Setty AR, Curhan G, Choi HK. Obesity, waist circumference, weight change, and the risk of psoriasis in women: Nurses’ Health Study II. Arch Intern Med. 2007;167(15):1670-1675.
12. Sterry W, Strober BE, Menter A; International Psoriasis Council. Obesity in psoriasis: the metabolic, clinical and therapeutic implications. Report of an interdisciplinary conference and review. Br J Dermatol. 2007;157(4):649-655.
13. Qusreshi AA, Choi HK, Setty AR, Curhan GC. Psoriasis and the risk of diabetes and hypertension: a prospective study of US female nurses. Arch Dermatol. 2009;145(4):379-382.
14. Gisondi P, Tessari G, Conti A, et al. Prevalence of metabolic syndrome in patients with psoriasis: a hospital-based case-control study. Brit J Dermatol. 2007;157(1):68-73.
15. Kurd SK, Troxel AB, Crits-Christoph P, Gelfand JM. The risk of depression, anxiety, and suicidality in patients with psoriasis: a population-based cohort study. Arch Dermatol. 2010;146(8):891-895.
16. Herron MD, Hinckley M, Hoffman MS, et al. Impact of obesity and smoking on psoriasis presentation and management. Arch Dermatol. 2005;141(12):1527-1534.
17. Poikolainen K, Reunala T, Karvonen J, Lauharanta J, Kärkkäinen P. Alcohol intake: a risk factor for psoriasis in young and middle aged men? BMJ. 1990;300(6727):780-783.
18. Rapp SR, Feldman SR, Exum ML, Fleischer AB Jr, Reboussin DM. Psoriasis causes as much disability as other major medical diseases. J Am Acad Dermatol. 1999;41(3 Pt 1):401-407.