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From the Population Studies Center, University of Pennsylvania, Philadelphia, Pennsylvania.
Address for reprints: Jamie Mihoko Doyle, Population Studies Center, University of Pennsylvania, 3718 Locust Walk, Philadelphia, PA 19104.
| ABSTRACT |
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Key Words: Race ethnicity clinical trials measurement FDA genetics regulations pharmacology
| WHAT DO RACE AND ETHNICITY MEASURE? |
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Endogenous Factors
Despite the arbitrary and fluid nature of racial and ethnic categories,
they are critical signposts and confound relationships between drugs and drug
response for 2 reasons. First, beginning from an endogenous perspective, race
and ethnicity capture important dimensions of a person's culture, diet, and
health
behaviors.2,15-17
Prior studies provide compelling evidence that the 3 aforementioned
characteristics affect both drug response measurements and dosing ranges for
safety.18-22
For instance, drug pharmacokinetics may be variable because of race-specific
or ethnic-specific diets, which affect drug absorption and
metabolism.15,23
Furthermore, the interpretation of questions asked about adverse events and
disease progress after administering a drug to patients may also vary because
of cultural differences in beliefs about medicine and medical
practice.24,25
These factors can exert a powerful influence on the generalizability of
clinical
studies.15,24
Exogenous Factors
Second, exogenous factors known as neighborhood or environmental effects
are also intimately tied to race and ethnicity. This area of research focuses
on how a given stratification system affects health. Exogenous factors should
not be confused with individual-level measures of social class, although they
can be closely related in some situations. To simplify and illustrate the
potential importance of exogenous factors in the present context, I will
amalgamate these perspectives into 2 related areas: psychosomatic responses
and neighborhood effects. Psychosomatic responses refer to physical processes
initiated by the mind in reaction to mental or emotional stress. Some
researchers refer to these catalysts broadly as stressors. This perspective
emphasizes the role of allostasis and, specifically, allostatic load.
Allostasis refers to "physiological mediators such as adrenalin from the
adrenal medulla, glucocorticoids from the adrenal cortex, and cytokines from
cells of the immune system [that] act upon the receptors in various tissues
and organs to produce effects that are adaptive in the short run but can be
damaging if the mediators are not shut off when no longer
needed."26(p10)
Researchers hypothesize that racial and ethnic differences in many chronic diseases can be attributed to allostatic load, which is the physiologic costs of persistent allostasis27 caused by persistent social inequality. The effects of allostatic load are linked to the progression of numerous diseases and biological processes from type 2 diabetes to the suppression of immune responses.26 This framework has been particularly insightful for health disparities among African Americans because a growing body of literature documents that African Americans disproportionately experience race-related stressors, which, in turn, affects physical and mental health via allostatic load.28-31 The lasting effects of racial stratification on physical health are also documented in other medical and sociologic literature.32-36
Alternatively, researchers focusing on neighborhood effects cite the potential importance of environmental influences and social context as fundamental causes of health disparities,12,37,38 although direct evidence of the causal role of neighborhood context is still a matter of debate.39 For example, several studies find that the concentration of poverty, substandard housing conditions, and deteriorating infrastructure in poor minority neighborhoods is associated with blacks having a higher prevalence of asthma as compared to other racial groups.40,41 From an exogenous perspective, minority status is a proxy for external exposure to stressors and/or environmental toxins and allergens from neighborhood environments that can interact with genes, drug response, and health outcomes. Clearly, the information captured by asking the simple question, "What is your race?" entails greater complexity than commonly believed.
| CONCLUSION: RACE AND ETHNICITY IN LIGHT OF ADVANCES IN PHARMACOGENOMICS |
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Genetics will not erase the importance of race and ethnicity because race and ethnicity do not measure genetic composition; the 2 capture different phenomena. Unlike genes, racial and ethnic categories are social constructs, and 2 persons with identical genetic makeup may well self-identify as being of a different race or ethnic origin. Furthermore, race and ethnic categories have been subject to change over time, and a person's self-identification may vary according to the context, wording, and format of the question asked. Yet, despite the fluid nature of the concept, self-identified race and ethnicity can capture something that genes cannot; namely, aspects of culture, behavior, diet, environment, and feature of social status that commonly used measures of socioeconomic status, such as income, education, and occupation, cannot measure. On the other hand, genetic biomarkers provide insight into disease pathology and drug response at the intracellular level. Yet neither is fully informative alone. If collected and interpreted correctly,* both pharmacogenomics and race and ethnic indicators can synergistically improve measurements of drug efficacy and safety with the potential of attenuating health disparities by race and ethnicity.
| ACKNOWLEDGEMENTS |
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* Requirements on how to collect and interpret data on race and ethnicity are
not currently outlined in the Code of Federal Regulations (CFR). For instance,
21CFR314.50 SS 5(V) states, "the effectiveness data shall be presented
by gender, age, and racial subgroups and shall identify any modifications of
dose or dose interval needed for specific
subgroups"43
but does not state which groups to include or how to collect such data. The
Food and Drug Administration issued a guidance for industry,
however.44 Comments
from the Clinical Data Interchange Standards Consortium Submission Data
Standards are examples of how some researchers misunderstand what race and
ethnicity measure in clinical trials
research.45 For
instance, in their comments they state, "the selection of multiple
[racial] categories will cause subjects who are not genetically alike to
appear as if they are, and correlations that are indeed due to race will be
missed (false negatives)." ![]()
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