Do not discount the diagnosis of VKH based on race: self-reported race and ethnicity of patients with Vogt-Koyanagi-Harada disease in a predominantly white population

Vogt-Koyanagi-Harada disease is typically reported in patients of certain races and ethnicities; most commonly those of Asian, Hispanic or Middle-Eastern origins as well as First Nations and Métis and Inuit [7,8,9,10,11,12].

One possible explanation for this is the higher number of melanocytes in certain tissues (such as skin, choroid, internal ear) in these populations, as the most widely accepted hypothesis for the pathogenesis of VKH disease is a CD4 + T-lymphocyte associated direct cellular response against melanocytes and probably free melanin [13].

We had noted that we saw more Caucasian and African-American patients with VKH than typically reported in the literature, so undertook a formal assessment of the race and ethnicity of our patients with VKH.

Publications from the United States report a high number of Hispanic patients in their cohorts. Beniz et al. from Los Angeles, California described 48 patients diagnosed with VKH. 13 75% of patients were Hispanic, 10% White, and 4% Black. Rubsamen and Gass reported that of 26 patients with VKH seen at Bascom Palmer Eye Institute in Miami, Florida, 54% were Hispanic, 23% Black, 14% White, and 9% Asian [14]. In these US reports the prevalence of White and Black/African-American patients among VKH patients is lower than in our cohort, in which the prevalence of White, Black/African-American and Hispanic patients were each 28.1%. In our series both White and Black/African-American patients were overrepresented, and Hispanic or Latino ethnicity was underrepresented compared to other series from the US. A possible explanation for this might be the general racial and ethnical distribution of these US regions. In the 2010 census results the racial distribution and Hispanic origin in Los Angeles was: 49.8% White, 9.6% Black/African-American, 11.3% Asian, and 23.8% Some Other Race. 48.5% of people reported Hispanic or Latino origin (among all races). In Miami-Dade County, Florida 73.8% were White, 18.9% Black/African-American, 1.5% Asian, and 65.0% reported Hispanic or Latino origin Compared to Chicago both places have a much greater Hispanic population [6]. Even though VKH is more common in Hispanic patients, due to the higher percentage of White and Black/African-American patients in the Midwest, both of these groups are overrepresented in our cohort.

In our cohort complete VKH was the least common diagnosed form of VKH based on the revised VKH diagnostic criteria [4]. This is in line with other reports, and can be explained due to the fact that in this form both symptoms typical of the acute phase of the disease and skin findings- that develop in later stages- have to be present [9, 15]. Although in the literature incomplete VKH seems to be the most common form reported, in our cohort it was only the second most common form following probable VKH. One explanation for this could be that, the clinical diagnosis of VKH has become more common with the advent of better imaging, allowing the diagnosis to be made in the absence of systemic findings.

There are a number of caveats of our study. Most importantly are its retrospective nature and the relatively low number of patients. However, since VKH is an orphan disease, our patient population is still among the larger ones reported in the literature. Another drawback is the possibility of selection bias through our institution’s tertiary referral nature, and due to insurance issues. Unfortunately these issues cannot be overcome unless a state or nationwide registry system is instituted to register all patients diagnosed with an orphan disease. It is also difficult to directly compare the regional demographics from the exact catchment area of our patient population, as we are limited to city, county, and state census data.

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