NEW YORK — From clinical trials to textbooks, patients with darker skin types who have psoriasis overall — and Black patients in particular — are underrepresented, which might at least partially explain why clinicians are slow to recognize nail involvement, even when the skin disease has already been diagnosed, according to Shari R. Lipner, MD.
In a recently published review of 45 randomized controlled trials of therapies for nail psoriasis, almost all included information about the gender of the patients enrolled, but only about 35% reported race and/or ethnicity, Lipner, associate professor of dermatology, Weill Cornell Medical College, New York, said at the Skin of Color Update 2023. The proportion climbed to 59% in trials that included at least one study site in the United States, although representation of non-White patients in studies conducted in the United States was not proportional to the population (13.4% vs. 39.9%), said Lipner, senior author of the review.
Black Patients Largely Unrepresented in Photos
When an Internet search was conducted for images of nail psoriasis, the proportion of images fell as the number of the Fitzpatrick scale increased. Fitzpatrick skin types 1 or 2 represented 70% of the images, skin types 3 to 4 represented about 27%, leaving just 3% represented by darker skin types, Lipner said.
"Unfortunately, things are not much better if you look at the dermatology and nail-specific textbooks. In fact, the percentages we see are almost identical," said Lipner, noting that her review of images suggested that only about 3% of images in textbooks are of Fitzpatrick skin types 5 or 6, an obstacle for clinicians learning to recognize nail involvement in skin of color patients with psoriasis.
Data from the 2009-2010 U.S. National Health and Nutrition Examination Survey (NHANES) confirms that psoriasis is less common in Blacks (1.9%) and Hispanics (1.6%) than Whites (3.6%). But these lower numbers still translate into substantial numbers nationally. Of those with psoriasis, the lifetime incidence of nail involvement has been variously estimated between 80% and 90%, Lipner said.
In about 10% of patients with psoriasis, nail involvement is isolated, occurring in the absence of skin lesions, a proportion that appears to be similar in Blacks and Whites according to Lipner.
Patient Characteristics Similar by Race
In a study conducted at her own center, many of the characteristics of psoriasis were similar when those with a Fitzpatrick skin type 4 or higher were compared to those of 3 or lower. This included male-female distribution, smoking history, and presence of accompanying psoriatic arthritis. There was one discrepancy between lighter and darker skin.
"The big difference was that it took almost 3 years longer [on average] for darker skin to be diagnosed, and there was worse severity of disease," Lipner said.
Like cutaneous manifestations of psoriasis, there are differences in appearance in the nail, many of which are simply produced by how skin color alters the appearance, such as the brownish hue of erythema in darker versus lighter skin. Lipner also noted that many of the features, such as keratosis, can be more severe in patients with darker skin types, but this is likely because of the delay in diagnosis.
The problem with overlooking nail psoriasis in patients of any skin color is the significant and independent adverse impact imposed by nail disease on quality of life, she added. She recounted the case of a 22-year-old Black patient whose nail psoriasis was overlooked even as she was being treated for her skin lesions.
"The diagnosis of nail psoriasis was missed for 3 years," said Lipner, noting that the nail involvement was not trivial. "She had trouble doing her daily activities of life, but also, she was very embarrassed by her nails, not surprisingly."
The problem of underrepresentation of Blacks in photos depicting nail diseases is not going unnoticed.
"Recently, there has been a concerted effort on the part of authors and editors to include more images of skin of color patients in published articles and textbooks," said Jane S. Bellet, MD, professor of dermatology, Duke University, Durham, N.C.
An expert in nail disorders, particularly in children, Bellet said in an interview that this trend "must continue and increase in volume." She said that the need for more images of nail disease in skin of color is not restricted to textbooks but includes "other learning materials, such as online atlases."
Lipner and Bellet reported no potential conflicts of interest relative to this topic.
This story originally appeared on MDedge.com, part of the Medscape Professional Network.
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Lead image: Taigis | Dreamstime.com
Cite this: Nail Psoriasis in Black Patients Often Overlooked - Medscape - Nov 28, 2023.
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