Ethnicity in Stroke: Practical Implications

To the Editor: I read with interest the editorial of Drs Fustinoni and Biller on ethnicity and stroke.1 The authors give several examples to demonstrate the dark side of “ethnicity” as an epidemiological variable. I agree that ethnicity is a complex, inherently heterogeneous concept influenced by different cultural and socioeconomic factors.2 The authors make the point that ethnicity is neither precise nor easily measured. However, I would like to discuss some issues of potential interest. First, ethnicity is derived from a Greek word meaning “population” or “tribe.” The criteria to define ethnicity have varied worldwide during the past decades. Therefore, criteria to classify ethnic groups may vary from one country to another.2 3 It is well known that most classifications have a bias. However, it is crucial to identify population subgroups to easily recognize and differentiate risk factors and, subsequently, patterns of disease. Thus, classifications are necessary in clinical practice and research, even if not perfect. It is the duty of the clinical investigator to use the most precise definition possible. Ethnic groups may be classified by using different criteria, such as geographic origin; migratory status; self-defined, past generation criteria; and tribe origin, among others. In addition, ethnicity depends on the context in which the definition is made.4 The same criteria are not necessarily valid for different countries. Second, the authors mention that “ethnic categories are usually not defined in scientific reports, which results in dubious findings that are difficult to compare.” Of course, poorly defined groups will contribute more confusion than clarification to a given topic. However, the existence of poorly designed studies does not justify the elimination of all data derived from other good reports. Third, Fustinoni and Biller cite questionable examples that have been used to criticize ethnicity, such as, “What is black …