Psoriasis occurs worldwide and its prevalence differs among racial groups. Certain racial groups may also be more genetically predisposed to develop psoriasis.
Higher prevalences seem to be found in Scandinavia (3% to 4.8%), Malaysia (4% to 5%), East Africa (1.25% to 3%), and South Africa (4% to 5%), and lower prevalences are seen in West Africans (0.3% to 0.8%), African Americans (0.45% to 1.3%), Southeast Asians (0.4% to 2.3%), Indians and East Asians (~0.3%), and the indigenous populations of the Americas (nearly absent).
The clinical features of psoriasis are similar across racial groups; however, darker skin phototypes show a tendency toward violaceous plaques, gray scale, and postinflammatory dyspigmentation.
The treatment of psoriasis is similar across racial groups. Traditional medicine is used by certain populations.
Psoriasis is a chronic, immune-mediated, inflammatory, and hyperproliferative disease of the skin that presents in a number of clinical forms that are similar across racial groups. The onset of the disease and its severity are strongly influenced by age and genetics, and may be provoked by a variety of factors such as physical injury to the skin, systemic drugs, infections, and emotional stress. Psoriasis is a systemic disease process and is associated with inflammatory arthritis, cardiovascular disease, and metabolic syndrome. The incidence of psoriasis is worldwide in distribution, but its prevalence varies by racial groups and geography. The treatment of psoriasis varies minimally among this groups.
Psoriasis appears to be most prevalent in northern European populations, particularly in Scandinavians, in whom the peak prevalence approaches 5%. Elsewhere in Europe, the prevalence ranges from 0.7% to 2.9%. In the United States, it ranges from 1.4% to 3.2%. Psoriasis is observed less frequently in people with darker skin phototypes. Differences in psoriasis prevalence may be due to differences in genetics and environmental exposures. It should be noted that with the exception of a few studies in India, China, Japan, the African continent, and among African Americans, large-scale, population-based studies of the prevalence of psoriasis in people with skin of color have yet to be reported. There are very few published studies on psoriasis in Native Americans and the Latin American populations of North, Central, and South America. In addition, studies vary in methodologies and sample sizes. Table 24-1 summarizes the available data.
TABLE 24-1Prevalence of psoriasis: ethnic and geographic comparison ||Download (.pdf) TABLE 24-1 Prevalence of psoriasis: ethnic and geographic comparison
|Country or ethnicity ||% of dermatology patients with psoriasis ||% of overall population with psoriasis ||Details |
|Arctic Kasach’ye75 || ||11.8 || |
|Norway75 || ||3–4.8 || |
|Norway, Lapp76 || ||1.4 (n = 2963) || |
|Norway77 || ||1.1, 1.4, 1.4 || |
|Norway78 || ||4.2 || |
|Sweden77 || ||2.0 || |
|Denmark77 || ||2.8 || |
|Faroe Islands79 || ||2.8 || |
|United Kingdom77 || ||0.8, 1.5, 1.9 || |