Mixed Race Studies

Ethnicity and Stroke: Beware of the Fallacies

Stroke
Volume 31, Issue 5 (May 2000)
pages 1013-1015
DOI: 10.1161/​01.STR.31.5.1013

Osvaldo Fustinoni, MD
Departments of Neurology
University of Buenos Aires, Buenos Aires, Argentina

José Biller, MD, Professor of Neurology and Neurological Surgery
Loyola University, Chicago

The role of ethnicity in stroke has been the subject of a considerable number of published reports. A quick Medline search detected 454 citations on “ethnicity and stroke,” 386 on “stroke in blacks,” 251 on “stroke in African Americans,” and 74 on “stroke in Hispanics,” of which only a few can be mentioned here. There even exists a journal dedicated to ethnicity and health.

However, the assumption that ethnicity is an isolated epidemiological variable delineating clinically distinct disease subgroups is controversial. The very concept of the word may be confounded with race (“black”), a common language or culture (“Hispanic”), a shared geographic origin (“Asian”), or a presumed common descent with diffuse boundaries (“Caucasian”). Ethnic categories are usually not defined in scientific reports, which results in dubious findings that are difficult to compare. The idea that a socially defined variable may reveal biological differences is fallacious, leading dangerously to biological determinism. For example, the genetic variation between races, traditionally classified on phenotype, is only slightly greater (10%) than that between nations (6%), and much larger within a local population (84%). Moreover, the genes responsible for skin color are few and are not associated with genetic markers for disease.

Ethnicity as a variable may be too greatly influenced by cultural attitude and therefore biased. In the past, this attitude led to the entire invention of diseases on the basis of race. At a time when the genetic inequality of races was considered obvious, the existence of these diseases was not questioned. In the present, ethnicity may be used euphemistically to avoid racist implications. A survey of 48 medical schools in the United States revealed that up to 91% of clerkship directors answered “yes” or “variable” after being queried whether students were taught by example to use the terms “black” or “white” when introducing case presentations. In another study, “black” patients were far more likely than “whites” to be racially identified at morning report. As recently as 1991, arterial hypertension has been related to skin color, even allowing for the fact that darker “blacks” may as a consequence be poorer and suffer more psychosocial stress.

Ethnic classification may vary from one community to another, as the perception of an ethnic group may be different across countries. As Caldwell and Popenoe put it, “what is black to someone from the United States may be white to a Brazilian or a Caribbean islander.” It may be added that the authors of the present editorial, both of European descent and born and raised in Spanish-speaking countries, would probably be classified as “Hispanic” in the US, although neither is of Spanish descent. Obviously, there is no such thing as a “Hispanic” ethnic group in Spain or Latin America.

Ethnicity is not a dichotomous variable, such as gender. How black is black? How is a person classified whose father is “white” and mother “black”? What about “mixed” grandparents? How does one classify a phenotypically “black” (by US standards) Spanish-speaking national from Central America? How are his children classified? Finally, how white is white? Do a Scot from Edinburgh and an Italian from Milan belong to the same ethnic group?…

…To avoid the shortcomings linked to classification, it has been proposed (and is now used in many reports) that patients entering population studies “self-classify” their ethnicity, assuming that “racial and ethnic categories are understood by the populations questioned.”

However, misinterpretation, confusion, and self-reclassification have been found in these cases. One striking example is that the category “South and Central American” was thought by respondents in one census to refer to natives of the south and central United States!…

…The consequences of flawed ethnicity research may lead to the assumption that ethnic minorities are an unhealthy social burden, that there are “ethnic” diseases which separate specific groups from the general population, that consequently they do not merit any further attention, and that “whites” are the “gold standard” of health. All this could do nothing but fuel racial prejudice…

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