Race-based Therapy for Hypertension: Possible Benefits and Potential Pitfalls

Keith C. Ferdinand; Daphne P. Ferdinand

Disclosures

Expert Rev Cardiovasc Ther. 2008;10(6):1357-1366. 

In This Article

Race/Ethnicity Definitions

The Human Genome Project has confirmed that, to a large extent, humans are essentially the same, with as great or greater variation within self-defined racial groups as across groups.[1] Research on human genomic variation increasingly challenges the validity of the term 'race' in describing human populations and making inferences on that basis. Biomedical and scientific literature and recent studies by leading human genetic researchers note essential similarities among African, European and Asian population groups. On the other hand, ancestry, rather than race, can provide beneficial information, as demonstrated by the direct assessment of disease-related genetic variation.[2] Insight into human genetic variation has grown rapidly over the last several years, with single-nucleotide polymorphisms being the most common form of assessing DNA variation in the human genome. Small, but significant, differences in polymorphisms appear to be as informative as markers of ancestry, depicted via histograms.[2] On the other hand, the biological variation in humans does not meet the criteria for phylogenetic subspecies or races and there are inconsistencies in the use of these terms. In addition, genetic ad-mixing will continue to confound any race-based treatment decisions; while in-migration of Blacks in the USA may be currently negligible, intermarriage of Hispanics and Asians with the majority population continues at a rapid pace. Even more importantly, any genetic susceptibility to hypertension, based on ancestry, is greatly affected by environmental factors, specifically obesity and sodium intake, and these factors explain much of the observed disparities in the prevalence and response to medications. Furthermore, skin pigmentation is of little value as a marker of ancestry or the definition of a population.

The USA Office of Management and Budget (OMB) has set standards for using race and ethnicity in research.[70] The race categories include self-identified 'Blacks or African-Americans', 'Asians', 'American Indians or Alaskan natives', 'Native Hawaiians or other Pacific Islanders', 'Whites or Caucasians', 'some other race' and 'two or more races'. 'Ethnicity' is not based on race, but is a USA designation related to Hispanic or Latino ancestry.

As presently used, 'White' refers to having origins in any of the original peoples of Europe, the Middle East or North Africa. 'Black or African-American' connotes persons self-described as having origins in any of the Black racial groups of Africa. Although this group is predominantly comprised of descendants of Africans brought to the USA during the slave era, it also includes more recent migrants, primarily from continental Africa and the Caribbean. 'American Indian and Alaskan Native' refers to individuals having origins in any of the native or original peoples of North and South America (including Central America). 'Asian' refers to those having origins in any of the original peoples of the Far East, Southeast Asia or the Indian subcontinent. Sites of origin for Asians include, for example, Cambodia, China, India, Japan, Korea, Malaysia, Pakistan, the Philippine Islands, Thailand and Vietnam. 'Native Hawaiian and Other Pacific Islander' refers to having origins in any of the original peoples of Hawaii, Guam, Samoa or other Pacific Islands. 'Some other race', an increasingly common self-classification, was added for respondents who did not desire to identify with the five existing OMB racial categories. Ethnicity, as a category, can describe persons of any racial group based on being 'Hispanic or Latino'. This term refers to a person of Cuban, Mexican, Puerto Rican, South or Central American or other Spanish culture or origin, regardless of race. Hispanics are also asked to report the race or races they considered themselves to be.

The US population, by percentage, shows a trend towards increased proportions of citizens identified as minorities. Based on the US Census Bureau's projected population of race and Hispanic origin by 2010, the USA population will be approximately 308,936,000, with nearly 245 million classified as White, comprising 79.3% of the population. Of the other racial groups, 40,454,000 will be defined as Black (13.1%), 14,241,000 as Asian (4.6%) and 9,246,000 as American Indian or Alaska Natives, Native Hawaiian and other Pacific Islanders (3.0%). A total of 47,756,000 individuals will be classified as Hispanic or Latinos of any race, comprising 15.5% of the population.[71]

Unfortunately, there are undeniable disparities related to health and healthcare issues among racial/ethnic groups in the USA, including hypertension and CVD. Accordingly, the US FDA has specific guidance for collecting and reporting race and ethnicity information in clinical research.[72] The FDA recommends a standardized approach using categories developed by the OMB for race and ethnicity.

There are tremendous challenges in the writing and interpretation of medical literature using race and ethnicity. First of all, definitions have changed and will continue to do so. Also, populations increasingly merge, making definitive comparisons practically impossible, with limitations in the validity of race/ethnicity data. Moreover, there is the potential to utilize race as an independent risk factor rather than a risk marker, underestimating the impact of environmental conditions. In this article, more data were found regarding US Blacks or African-Americans than for other racial and ethnic groups. Thus, this population will be described in more detail.

Hypertension is largely uncontrolled across all racial/ethnic groups. Recent data regarding the age-adjusted prevalence for high blood pressure (BP) in adults in the USA suggested that African-American women have the highest rates (41.4%), even compared with African-American men (39%).[3] This increased prevalence is in contrast to the estimates for White women (28.0%) and White men (28.5%).[3,4] Moreover, Mexican-American women and men had the even lower prevalence rates of 27 and 26.2%, respectively.[3,4] Nevertheless, possibly related to a lack of access to care and health insurance, the lowest rates of control were in Mexican-Americans at 25.1% and, despite high levels of awareness, African-Americans at 36.3%.[3,4] In consideration of all this data, CVD-related disparities based on race and ethnicity remain a major cause for concern, and an improved understanding of the source of disparities is crucial.[3,5,6,73,74]

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