Endothelial Function: The Impact of Objective and Subjective Socioeconomic Status on Flow-Mediated Dilation
Denise C. Cooper
0
Ph.D.
0
Milos S. Milic
0
M.D.
0
Ph.D.
0
Paul J. Mills
0
Ph.D.
0
Wayne A. Bardwell
0
Ph.D.
0
Michael G. Ziegler
0
M.D.
0
Joel E. Dimsdale
0
M.D.
0
0
W. A. Bardwell Moores University of California San Diego Cancer Center
,
La Jolla, CA, USA
1
0804,
La Jolla, CA 92093-0804, USA
Background Although objective and subjective indicators of socioeconomic status (SES) are linked to cardiovascular disease (CVD), little is known about their relationship to endothelial dysfunction, which often precedes CVD. Purpose This study examined how objective and subjective SES relate to brachial artery flow-mediated dilation (FMD). Methods FMD was assessed in 72 healthy adults (mean age 36 years). The MacArthur Scale of Subjective Social Status assessed perceived social standing in the USA (SSSUSA) and local community (SSS-Community). Objective SES measures included income and the Hollingshead TwoFactor Index of Social Position (education, occupation). Results Adjusted regressions revealed that SSS-Community positively correlated with FMD (p<0.05) and explained 8% of the variance. No other SES measures were significant for FMD. The association between FMD and SSS-Community remained significant (p<0.01) after adjustment for objective SES and other covariates. Conclusions Lower subjective social status in one's community may be linked to CVD via impaired vasodilation.
-
Researchers in several countries note that socioeconomic
status (SES) shows graded inverse associations with
cardiovascular morbidity and mortality, independent of
traditional risk factors [1]. Recent declines in
cardiovascular disease (CVD) have been less prominent in people of
lower social classes [2]. Although reduced access to health
care likely plays a role in many countries, such as the USA,
the SESCVD gradient also is found in countries with
universal health care [3]. Social class differences in the
prevalence of adverse health behaviors, such as smoking
and physical inactivity, also contribute to the inverse
relationship between SES and CVD [4]. However, studies
show that the SESCVD gradient is still found after
adjusting for differences in health behaviors and traditional
risk factors [1, 2].
Although SES has been linked to a variety of CVD
measures [57], little is known about the relationship
between SES and endothelial dysfunction. Endothelial
dysfunction refers to shifts in endothelial processes that
lead to decreased vasodilation. With normal function of the
endothelium, vascular homeostasis is maintained, and
vasoconstriction is limited by secretion of a variety of
substances (e.g., nitric oxide), which cause vascular smooth
muscle relaxation and artery dilation [8]. Endothelial
dysfunction is observed in the early stages of
atherosclerosis and is associated with increased plaque rupture in
myocardial infarction and other adverse outcomes [8, 9].
Endothelial function can be evaluated with the emerging
technique of flow-mediated dilation (FMD), which
noninvasively measures endothelium-dependent vasodilation
elicited by reactive hyperemia [10]. In response to
increased shear stress induced by reactive hyperemia, the
endothelium is stimulated to produce and release nitric
oxide, which relaxes vascular smooth muscle and produces
a measurable increase in artery diameter. FMD refers to the
percentage of post-stimulation change in brachial artery
diameter relative to baseline [11]. It is highly correlated
with invasive endothelial testing and is inversely associated
with cardiovascular risk [1215]. Several prospective
studies support a prognostic value for FMD in predicting
adverse cardiovascular outcomes among community
samples and patient populations [1621].
Parallel to research on behavioral and psychosocial risk
factors for CVD [2], several studies suggest that unhealthy
behaviors (e.g., physical inactivity) [22] and a variety of
psychosocial characteristics (e.g., depressed mood, stress)
[2326] are linked to endothelial impairment. Despite the
substantial literature linking CVD to SES, endothelial
function has not been well studied with regard to SES
among adults. However, some null findings have been
reported for FMD in studies of childhood SES, as measured
by the occupational status of the childrens parents [2729].
Those nonsignificant findings for childhood SES could
have been due in part to the young ages of the subjects and
to the potential limitations of objectively measured SES
(e.g., parental occupation). Although occupational status
and other objective measures of SES (e.g., education,
income) have been linked to CVD [14], these narrowly
defined measures cannot capture all the dimensions of
social status that have potential relevance to health [30].
Perceptions about ones standing in society or on the
social ladder relative to other people may reflect a
cognitive averaging of several standard markers of social
class (e.g., income, education, occupation, spouses
occupation, home ownership), along with more nuanced aspec (...truncated)