Abstract
Data on research participants and
populations frequently include race, ethnicity, and gender as
categorical variables, with
the assumption that these variables exert their
effects through innate or genetically determined biologic mechanisms.
There
is a growing body of research that suggests,
however, that these variables have strong social dimensions that
influence health.
Socioeconomic status, a complicated construct in
its own right, interacts with and confounds analyses of race/ethnicity
and
gender. The Academy recommends that research
studies include race/ethnicity, gender, and socioeconomic status as
explanatory
variables only when data relevant to the underlying
social mechanisms have been collected and included in the analyses.
During recent decades, our understanding of the biological and psychosocial bases of diseases affecting individual children
has markedly increased.1,,2
The capacity to apply newly derived information from molecular and
genetic science toward preventive child health care will
continue to grow in the coming years. Although
biological research is necessary and valid, studies that do not address
the
importance of social determinants as fundamental
causes or contributors to disease and unfulfilled potential limit the
scope
and impact of research conclusions.3
In the United States, data on research
participants and populations frequently include race, ethnicity, and
gender as categorical
variables, with the assumption that these variables
exert their effects through innate or genetically determined biologic
mechanisms. There is a growing body of research that
suggests, however, that these variables have strong—and in many areas
predominantly—sociological and psychological
dimensions. Because data are collected and research questions are
formulated
in ways that generally do not include the social as
well as biological dimensions of these variables,4,,5
it is often difficult to disentangle the biological from the social
dimensions. The purpose of this subject review is to
highlight the interrelationships among factors such as
race, ethnicity, and gender, viewed as social constructs, along with
socioeconomic status, and to stimulate appropriate
definition and analysis of these variables within any study that
proposes
mechanisms of disease associated with them.
RACE AND ETHNICITY
It is standard practice to describe
participants and populations in terms of “race” or “ethnicity.” For
example, the decennial
census has classified respondents according to the
1977 Office of Management and Budget Directive 15, which includes 4
racial
categories (American Indian or Alaskan Native,
Asian or Pacific Islander, Black, and White) and 2 ethnic categories
(Hispanic
Origin and not of Hispanic Origin). The recent
revision of this Directive6
has expanded these categories to 5, by separating Asian from Pacific
Islander and expanding the latter to “Native Hawaiian
or other Pacific Islander,” but the existence of
this small number of categories limits investigators to use only those
categories
to frame and analyze questions. The Revised
Directive 15 rejected the use of a “multiracial” category, but does
recommend
that the 2000 Census allow respondents to check
more than 1 category.
Although race historically has been viewed as a biological construct, it is now known to be more accurately characterized
as a social category that has changed over time and varies across societies and cultures.7 Racial disparities in health generally do not reflect biologically determined differences in the genome or physiology.8
Indeed, genetic differences between racial groups are small compared
with genetic differences within groups, so racial differences
in diseases are, to a significant degree, currently
unexplained.9
It is possible that racial prejudice (both individual and
institutional) as a social stress on groups of children and families
can influence health behaviors, such as eating
habits, activity levels, and substance use and abuse that might place
individual
children at increased risk for both short-term and
long-term health impairment and disease.10–12 In addition to effects on behavior, racial prejudice may influence access to and the quality of health services.11–13 Similarly, difficulties in definition and measurement, heterogeneities of populations, and ethnocentric interpretations of
research data8
make “ethnicity” an imprecise construct by which to attribute causal
relationships. Given that race and ethnicity are similar
in their social origins, that is, determined
predominantly by the relationships among groups who define themselves or
define
others, the term race/ethnicity is becoming more
widely used.
GENDER
Sex and gender are often used
interchangeably, but the former is a biologic characteristic, defined by
genetic and anatomic
features, whereas the latter is a social
characteristic, determined by culturally defined roles and behaviors.
Analogous to
race/ethnicity, the development of gender is a
function of relationships. Ironically, the genetic, physiologic, and
behavioral
differences between men and women have historically
been deemphasized, if not ignored, in research that has extrapolated
conclusions
based on male populations to women. In recent
years, recognition of the importance of considering differences between
men
and women as a salient independent variable in
research led the National Institutes of Health to include women as
participants
for special consideration in clinical research
grant applications, but the focus is primarily on the biological
variable,
that is, sex, rather than the social variable,
gender.14
Inclusion of both men and women as
participants in research studies is certainly a first step in
understanding sex and gender
differences in health and disease. However, given
the health correlates of the differences in the social roles and
behaviors
of men and women, any differences found are not
inevitable expressions of the biological factor. For example, the
increased
risk of anorexia and bulimia in girls likely
reflects perceived social pressures to adhere to culturally prescribed
norms
for body shape and size. Furthermore, socially
defined gender roles, expectations, and behavior can vary across both
time
and culture, as well as across subgroups of
individuals, defined socially by race/ethnicity and socioeconomic
status. For
example, the social and psychological pressures
experienced by an African-American woman might be very different from
those
experienced by a white woman, with these pressures
having differential impact on the long-term trajectory of disease.15
SOCIOECONOMIC STATUS
Analysis of the relationship among
biological and social variables is complicated, however, by the
difficulty in operationalizing
socioeconomic status, a complex concept consisting
of 2 aspects, both of which may exert influences on health directly or
through associated behaviors. One aspect includes
resources, such as education, income, and wealth and the other includes
status or rank, a function of relative positions in
a hierarchy, such as social class.16A recent National Institutes of Health conference examined measures of socioeconomic status and proposed ways to incorporate
a variety of these measures into health surveillance and research.17
Demonstrated racial/ethnic and gender
“effects” may be intricately related to socioeconomic factors, because
race/ethnicity
interacts with and is confounded by social class or
socioeconomic status. For example, environmental pollution may be more
intense in impoverished areas and may even be sited
in those areas because of discrimination based on race/ethnicity or
class.18
Consequently, it is difficult to disentangle the adverse consequences
of that pollution from the effects of discrimination.
Although most studies of such confounding and/or
interaction have focused on adults, the need for inquiries into such
factors
affecting child health is equally strong. Little is
known about the way that the relationships among these social factors
influence the health of children or their effects
on the trajectory of the development of adult disease.
Two domains of the relationship between
socioeconomic status and health are particularly active areas of
research, possibly
shedding light on the complexity of the mechanisms
whereby this multidimensional variable influences health. The first
domain
deals with the relationship between the extent of
discrepancies in socioeconomic status and health. Numerous studies have
documented the relationship between socioeconomic
status and health.19
Despite advances in quality and access to health care services, it is
noteworthy that the discrepancy in health status between
social classes has persisted over time, even though
the specific diseases that produce morbidity and mortality have
changed.20
Furthermore, standard measures of health correlate with the extent of
income discrepancy between rich and poor, and the extent
of income inequality appears to explain more of the
variation in health than is explained by other socioeconomic factors,
even the absolute level of income.20–22 Across industrialized countries, the greater the discrepancy in income distributions, the worse the health status of the
entire population.20 Data across individual states within the United States demonstrate a similar relationship.21,,22
The second domain of the relationship
between socioeconomic status and health explores the relationship
between childhood
socioeconomic conditions and adult health. In
Finland, for example, the childhood socioeconomic status of adult men
correlated
more closely with ischemic heart disease during
middle age than did their adult socioeconomic status.23 Further research is needed to clarify how the socioeconomic status of children affects both their current and future health
status.24
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