Racial differences in arterial stiffness and microcirculatory function between Black and White Americans.

BACKGROUND: Compared with whites, black Americans suffer from a disproportionate burden of cardiovascular disease (CVD). We hypothesized that racial differences in the prevalence of CVD could be attributed, in part, to impaired vascular function in blacks after adjustment for differences in risk factor burden. METHODS AND RESULTS: We assessed vascular function in 385 black and 470 white subjects (mean age, 48±11 years; 45% male). Using digital pulse amplitude tonometry (EndoPAT) we estimated the reactive hyperemia index (RHI), a measure of microvascular endothelial function, and peripheral augmentation index (PAT-AIx). Central augmentation index (C-AIx) and pulse-wave velocity (PWV) were measured as indices of wave reflections and arterial stiffness, respectively, using applanation tonometry (Sphygmocor). Compared with whites, blacks had lower RHI (2.1±0.6 versus 2.3±0.6, P<0.001), greater arterial wave reflections assessed as both PAT-AIx (20.4±21.5 versus 17.0±22.4, P=0.01) and CAIx (20.8±12.3 versus 17.5±13.3, P=0.001), and greater arterial stiffness, measured as PWV (7.4±1.6 versus 7.1±1.6 m/s, P=0.001). After adjustment for traditional CVD risk factors, black race remained a significant predictor of lower RHI and higher PAT-AIx and CAIx (all P<0.001) in all subjects and of higher PWV in men (P=0.01). Furthermore, these associations persisted in a subgroup analysis of "healthy" individuals free of CVD risk factors. CONCLUSION: Black race is associated with impaired microvascular vasodilatory function, and greater large arterial wave reflections and stiffness. Because impairment in these vascular indices may be associated with worse long-term outcomes, they may represent underlying mechanisms for the increased CVD risk in blacks.

A genetic risk variant for myocardial infarction on chromosome 6p24 is associated with impaired central hemodynamic indexes.

BACKGROUND: Genome-wide association studies (GWAS) have identified novel variants associated with myocardial infarction (MI) in Caucasians. We hypothesized that those variants whose mechanism of risk is currently unknown, confer risk via pathways mediating arterial wave reflections which is an increasingly recognized risk factor for cardiovascular disease. METHODS: Single-nucleotide polymorphisms (SNPs) at eight MI risk loci were genotyped and correlated with noninvasively determined pulse wave analysis (PWA)-derived central hemodynamic indexes (augmentation index (AIx); augmented pressure (AP); time to reflected wave (TrW) and central systolic blood pressure (SBP) and diastolic BP (DBP)) in two independent Caucasian populations including (i) those free of measured cardiovascular risk factors (n = 133) and (ii) a community-based population (n = 270). RESULTS: Of the eight SNPs examined in the healthy group, the variants at loci 6p24 (AIx and AP both P < 0.001, TrW P = 0.02) and 21q22 (AIx P = 0.002, TrW P = 0.037) were significantly associated with PWA indexes. In the replication group, only the 6p24 variant correlated with these phenotypes (AIx P = 0.005, AP P = 0.049, TrW P = 0.013). In the pooled population (n = 403), no new associations were identified but the association with 6p24 and AIx remained significant even after Bonferroni correction and adjustment for covariates including age, mean arterial pressure, height, gender, glucose, cholesterol, body mass index (BMI), and smoking (AIx (P = 0.03)). Each copy of the risk allele C increased the AIx by 3.5%. CONCLUSIONS: The GWAS discovered MI risk variant at 6p24 in the protein phosphatase 1 regulator gene (PHACTR1) is associated with adverse arterial wave reflection indexes and may mediate MI risk through this pathway.

Differences in systemic oxidative stress based on race and the metabolic syndrome: the Morehouse and Emory Team up to Eliminate Health Disparities (META-Health) study.

BACKGROUND: Classification schema such as metabolic syndrome may underestimate cardiovascular disease (CVD) risk in African Americans, despite a higher burden of CVD in African Americans. Oxidative stress results from an imbalance of prooxidants and antioxidants and leads to endothelial dysfunction that promotes vascular inflammation and atherosclerosis. Aminothiol markers of oxidative stress are associated with CVD risk factors and metabolic syndrome; however, little is known about racial differences in levels of oxidative stress. We sought to investigate whether oxidative stress would be higher in African Americans compared to whites independently of traditional risk factor burden. METHODS: We assessed oxidative stress in a biracial, community-based cohort. In 620 subjects (59% female, 52% African American) in the Morehouse and Emory Team up to Eliminate Health Disparities (META-Health) study, we measured plasma levels of glutathione, an intracellular antioxidant, and its redox potential as a ratio of reduced and oxidized glutathione (E(h) glutathione). RESULTS: African Americans had lower glutathione levels (P<0.001) compared to whites. There was a trend toward more oxidized E(h) glutathione (P = 0.07) in African Americans; however, this did not reach statistical significance. After adjustment for demographics and CVD risk factors, African-American race remained a significant correlate of lower glutathione levels (P<0.001) and a more oxidized E(h) glutathione (P = 0.04). After further adjustment for high-sensitivity C-reactive protein (hsCRP), glutathione remained significantly lower in African Americans (P = 0.001). African Americans with or without metabolic syndrome had lower glutathione levels compared to whites with or without metabolic syndrome, respectively (both P ≤ 0.001), and African Americans without metabolic syndrome had a more oxidized E(h) glutathione compared to whites without metabolic syndrome (P = 0.003). CONCLUSIONS: African Americans have higher levels of oxidative stress than whites, even after adjustment for differences in CVD risk factors and inflammation. Racial differences in oxidative stress may play a key role in understanding observed racial disparities in CVD.

Differences in weight perception among blacks and whites.

BACKGROUND: The prevalence of obesity is higher in blacks than whites, especially in black women, and is known to be associated with major cardiovascular disease risk factors, which are also more prevalent in blacks than whites. Weight perception may contribute to these differences if blacks are more likely to underestimate their weight. We explored race and gender differences in underestimation of weight using body mass index (BMI) and waist circumference (WC), after adjusting for other cardiovascular risk factors. METHODS AND RESULTS: We studied 219 white and 240 black women and men as part of the META-Health Study. Perceived weight was assessed over the phone and categorized into three categories: underweight or normal weight, overweight, or obesity. Height, weight, and WC were measured at a subsequent visit, and BMI was calculated. Logistic regression was used to compare the likelihood of underestimating actual weight category by race, before and after adjusting for sociodemographic, lifestyle factors, and medical history. In multivariate analysis, the odds of underestimating BMI category was greater than threefold in blacks compared with whites (OR 3.1, 95% CI 1.9-4.8) and was larger for black women than for black men (p<0.01 for interaction). When abdominal adiposity was taken into account by utilizing WC as a measure of weight, the observed difference in weight underestimation remained. CONCLUSION: Our data reveal a significant misperception of weight among blacks, particularly black women, who have the highest burden of obesity. A multifaceted approach with efficient identification of social, cultural, and environmental factors that give rise to obesity tolerance in blacks will provide potential targets for intervention, which may ameliorate weight misperception and the prevalence of excess weight in the black population.

Association of adiponectin with left ventricular mass in blacks: the Jackson Heart Study.

BACKGROUND: Blacks have a higher prevalence of left ventricular hypertrophy than whites. Several population-based studies have reported an inverse association between adiponectin and left ventricular mass (LVM); however, the relationship between adiponectin levels and LVM has yet to be defined in blacks. The Jackson Heart Study cohort provides an opportunity to test the hypothesis that the inverse association between adiponectin and LVM may be modified by risk factors common among blacks. METHODS AND RESULTS: The study population included 2649 black Jackson Heart Study participants (mean age 51±12 years, 63% women, 51% obese, 54% with hypertension, and 16% with diabetes). Multiple linear and spline regression was used to assess the association, with adjustment for demographic, clinical, and behavioral covariates. Among all the participants, there was a statistically significant but modest inverse association between adiponectin and LVM index. Hypertension and insulin resistance emerged as statistically significant effect modifiers of this relationship. The inverse association present among the normotensive participants was explained by obesity measures such as the body mass index. Among participants with both hypertension and insulin resistance, there was a significant direct association between adiponectin and the LVM index after multivariable adjustment (ß=1.55, P=0.04, per 1-SD increment in the adiponectin log value). CONCLUSIONS: The association between serum adiponectin and LVM among blacks in the Jackson Heart Study cohort was dependent on hypertension and insulin resistance status. Normotensive blacks exhibited an inverse adiponectin-LVM association, whereas participants with hypertension and insulin resistance had a direct association.

Association between depression and inflammation--differences by race and sex: the META-Health study.

OBJECTIVE: To test whether the association between depression and inflammation differs by race and sex. Depressive symptoms have been associated with higher levels of C-reactive protein (CRP). However, few studies have examined this association in samples including a significant number of African Americans, or examined whether the association differs by race and sex. METHODS: Depressive symptoms and CRP were assessed in 512 African American and white participants, age 30 to 65 years, as part of the community-based Morehouse and Emory Team up to Eliminate Health Disparities (META-Health) Study. Depression was determined by responses to the Beck Depression Inventory II (BDI-II). Multivariable linear regression models were used to adjust for demographic and metabolic risk factors. RESULTS: African American men had higher total BDI-II scores than white men (p = .03), whereas there was no difference in women. There was a significant race-sex-depression interaction in predicting CRP levels (p = .02). White women with mild to severe depressive symptoms had higher levels of CRP compared with those with minimal to no depressive symptoms (p < .05). There were no differences in levels of CRP by severity of depressive symptoms in white men or African Americans of either sex. Higher BDI-II scores were related to higher CRP levels in white women after adjusting for age and level of education (ß = 0.227, p = .006). However, the association was eliminated after further adjustment for metabolic risk factors (ß = 0.077, p = .35). CONCLUSIONS: Although depressive symptoms are associated with inflammation, the association varies by race and sex.

Interaction of sleep quality and psychosocial stress on obesity in African Americans: the Cardiovascular Health Epidemiology Study (CHES).

BACKGROUND: Compared with whites, sleep disturbance and sleep deprivation appear more prevalent in African Americans (AA). Long-term sleep deprivation may increase the risk of obesity through multiple metabolic and endocrine alterations. Previous studies have reported contradictory results on the association between habitual sleep duration and obesity. Accordingly, we aimed to assess whether sleep quality and duration are inversely associated with body mass index (BMI) and obesity and test whether these associations are modified by psychosocial stress, known to influence sleep quality. METHODS: A sample of 1,515 AA residents of metropolitan Atlanta, aged 30-65 years, was recruited by a random-digit-dialing method in 2007-08. The outcome obesity was defined by BMI (kg/m²) continuously and categorically (BMI ≥ 30 versus BMI < 30). Global sleep quality (GSQ) score was computed as the sum of response values for the seven components of the Pittsburgh Sleep Quality Index (PSQI) scale. GSQ score was defined as a continuous variable (range 0-21) and as tertiles. The general perceived stress (GPS), derived from the validated Cohen scale, was categorized into tertiles to test the interaction. Chi-square tests, correlation coefficients and weighted multiple linear and logistic regression were used to assess the associations of GSQ, GPS and obesity. RESULTS: The mean (standard deviation) age was 47.5 (17.0) years, and 1,096 (72%) were women. GSQ score categorized into tertiles was associated with BMI. Among women, after multivariable adjustment that included age, gender, physical activity, smoking status, education, total family income, financial stress and history of hypertension, hypercholesterolemia, diabetes and myocardial infarction, obesity was associated with sleep quality as assessed by GSQ continuous score, [odds ratio, OR (95% C.I.): 1.08 (1.03 - 1.12)], and with a worse sleep disturbance subcomponent score [OR (95% C.I.): 1.48 (1.16 - 1.89)]. Among all participants, stress modified the association between obesity and sleep quality; there was an increased likelihood of obesity in the medium stress category, OR (95% C.I.): 1.09 (1.02 - 1.17). CONCLUSION: Sleep quality was associated with obesity in women. The association of sleep quality with obesity was modified by perceived stress. Our results indicate the need for simultaneous assessment of sleep and stress.

High blood pressure trends in children and adolescents in national surveys, 1963 to 2002.

BACKGROUND: Secular trend data on hypertension in children and adolescents are scarce and inconsistent. In the face of growing obesity, we sought to assess high blood pressure (HBP) secular trends in children and adolescents enrolled in national surveys and to determine whether the HBP trend reversed its course with the rise in obesity. METHODS AND RESULTS: National survey data obtained from multistage probability sampling of the US noninstitutionalized population from 1963 to 2002 were examined; 8- to 17-year-old non-Hispanic blacks and whites and Mexican Americans were included. HBP ascertainment was based on age-, gender-, and height percentile-specific systolic and diastolic BPs. Weighted analyses were performed to account for the complex design. The BP, pre-HBP, and HBP trends were downward from 1963 to 1988 and upward thereafter. Pre-HBP and HBP increased 2.3% (P=0.0003) and 1% (P=0.17), respectively, between 1988 and 1999. Obesity increase, more so abdominal than general obesity, partially explained the rise in HBP and pre-HBP from 1988 to 1999. BP and HBP reversed their downward trends 10 years after the increase in the prevalence of obesity. Additionally, an ethnic and gender gap appeared in 1988 for pre-HBP and in 1999 for HBP; non-Hispanic blacks and Mexican Americans had a greater prevalence of HBP and pre-HBP than non-Hispanic whites, and males had a greater prevalence than females. CONCLUSIONS: HBP and pre-HBP in children and adolescents are on the rise. These new findings have implications for the cardiovascular disease public health burden, particularly the risk of a new cardiovascular disease transition. They reinforce the urgent call for early prevention of obesity and HBP and illustrate racial/ethnic disparities in this age group.

Race-gender differences in the association of trait anger with subclinical carotid artery atherosclerosis: the Atherosclerosis Risk in Communities Study.

This paper examines the association between trait anger and subclinical carotid artery atherosclerosis among 14,098 Black or White men and women, aged 48-67 years, in the Atherosclerosis Risk in Communities Study cohort, 1990-1992. Trait anger was assessed using the 10-item Spielberger Trait Anger Scale. Carotid atherosclerosis was determined by an averaged measure of the wall intimal-medial thickness (IMT) of the carotid bifurcation and of the internal and common carotids, measured by high-resolution B-mode ultrasound. In the full study cohort, trait anger and carotid IMT were significantly and positively associated (p = 0.04). In race-gender stratified analysis, the association was strongest and independent only in Black men, among whom a significant trait anger-carotid IMT relation was observed for both the overall trait anger measure (p = 0.004) and the anger reaction dimension (p = 0.001). In Black men, carotid IMT levels increased across categories of overall trait anger and anger reaction, resulting in clinically significant differences (67 microm (95% confidence interval: 23, 110) and 82 microm (95% confidence interval: 40, 125), respectively) from low to high anger. Sociodemographic, lifestyle, anthropometric, and biologic cardiovascular disease risk factors appear to mediate the relation in Black women, White men, and White women. In conclusion, these findings document disparate race-gender patterns in the association of trait anger with subclinical carotid artery atherosclerosis.

Trait anger and arterial stiffness: results from the Atherosclerosis Risk in Communities (ARIC) study.

The cross-sectional association between trait anger and stiffness of the left common carotid artery was examined in 10,285 black or white men or women, 48-67 years of age, from the Atherosclerosis Risk in Communities (ARIC) study cohort. Trait anger was assessed using the 10-item Spielberger Trait Anger Scale. Arterial stiffness was assessed by pulsatile arterial diameter change (PADC) derived from echo-tracking ultrasound methods; the smaller the PADC, the stiffer the common carotid artery. In men, trait anger was significantly associated with PADC, independent of the established cardiovascular disease risk factors (p=0.04). PADC decreased from the first (lowest anger group) to the second quintile of anger, but there was no progressive decrease thereafter. Also observed was a 13-microm (95% confidence interval [CI], 1-25) difference in the magnitude of PADC from the lowest to the uppermost quintile of anger (PADC [standard error], 421 [4] microm vs. 408 [5] microm). In women, the association was marginally significant (p=0.07). The low-high difference in the magnitude of PADC (PADC [standard error], 397 [3] microm vs. 406 [4] microm) was inverse (-9 microm 95% CI, -19 to 2). Conclusions indicate that very high trait anger is associated with arterial stiffness in men.

Quality care improvement program in a community-based participatory research project: example of Project DIRECT.

A continuous quality care improvement program (CQIP) was built into Project DIRECT (Diabetes Interventions Reaching and Educating Communities Together) to improve providers' patterns of diabetes care and patients' glycemic control. Project DIRECT consisted of a comprehensive program aimed at reducing the burden of diabetes in the vulnerable high-risk African-American population of southeast Raleigh, NC. Forty-seven providers caring for this target population of adult diabetes patients were included in this quasi-experimental study. At the initial session, providers learned about the CQIP components, completed a planning worksheet, and chose a CQIP coordinator. Educational events included continuing education in practices and through conferences by experts, and guideline distribution. Follow-up was accomplished through phone calls and visits. Effectiveness was measured by a change in prevalence of selected patterns of care abstracted from 1,006 medical charts. Appropriate statistical methods were used to account for the cluster design and repeated measures. At the fourth follow-up year, approximately 40% of providers still participated in the program. Among the providers who stayed in the program for the whole study period, most selected quality care patterns showed significant upward trends. Glycemic control indicators did not change, however, despite an increased number of hemoglobin A1c tests per year. A diabetes CQI program can be effectively implemented in a community setting. Improved performance measures were not associated with improved outcomes. These results suggest that a patient-centered component should reinforce the provider-centered component.

Arterial stiffness is greater in African Americans than in whites: evidence from the Forsyth County, North Carolina, ARIC cohort.

BACKGROUND: Impairment of arterial dilation is thought to occur earlier than arterial wall thickening in the atherosclerotic process. In comparison with whites, African Americans reportedly have a generalized attenuation of their vasodilation mechanisms. We set out to evaluate arterial stiffness and its correlates by ethnicity, hypothesizing that African Americans would have stiffer common carotid arteries (ie, lower arterial distension for a given systolic pressure) than their white counterparts. METHODS: The study population included 268 African Americans and 2459 whites, who were aged 45 to 64 years at baseline examination in 1986 to 1989, free of coronary heart disease and stroke/transient ischemic attack, from Forsyth County, North Carolina. The beta stiffness index and pulsatile arterial diameter change were derived from brachial blood pressure and from echo-tracked systolic and diastolic carotid arterial diameters. RESULTS: African Americans had stiffer carotid arteries than their white counterparts, with a right shift of the beta stiffness index distribution. After adjustment for selected cardiovascular risk factors, the mean beta stiffness index was 9% higher for African Americans (mean +/- SEM: 11.3 +/- 0.3) than for whites (mean +/- SEM: 10.3 +/- 0.1) among participants not taking antihypertensive medication. Socioeconomic status and comorbidities were differentially associated with arterial stiffness by ethnicity. Specifically, the association between these correlates and beta stiffness index was stronger in African Americans than in whites. CONCLUSIONS: This report on arterial mechanics in African Americans suggests that large artery stiffening either occurs earlier, or is more accelerated in African Americans than in whites in our sample, perhaps as a result of earlier exposure to multiple risk factors. This finding may have implications for hypertension prevention, as arterial stiffness is associated with the development of hypertension.

Perceived stress following race-based discrimination at work is associated with hypertension in African-Americans. The metro Atlanta heart disease study, 1999-2001.

There is increasing evidence of an association between stress related to job strain and hypertension. However little data exist on stress from racism and race-based discrimination at work (RBDW). The objective of this study was to investigate whether blood pressure (BP) outcomes are positively associated with stressful racism towards African-Americans from non-African-Americans as well as RBDW from other African-Americans. The metro Atlanta heart disease study was a population-based study which included 356 African-American men and women, aged >/=21 years, residing in metropolitan Atlanta, Georgia during 1999-2001. Perceived stress was self-reported by 197 participants for racism from non-African-Americans and 95 for RBDW from other African-Americans. Sitting systolic (SBP) and diastolic (DBP) BP were taken at a clinic visit and was the average of the last two of three BP measures. Hypertension was self-reported as physician-diagnosed high BP on 2 or more visits. Logistic and least-squares linear regression models were fit accordingly and separately for each type of stress, adjusting for age, gender, body mass index, and coping abilities. The likelihood of hypertension significantly increased with higher levels of perceived stress following racism from non-African-Americans, but not from RBDW from other African-Americans; adjusted odd ratios (95% CI) were 1.4 (1.0, 1.9) and 1.2 (0.8, 1.5) per unit increment of stress. The adjusted magnitude of SBP and DBP increase between low and very high level of stress, conversely, was greater when RBDW originated from African-Americans than racism from non-African-Americans. Stressful racism and RBDW encounters are associated with increased SBP and DBP and increased likelihood of hypertension in African-Americans. Future studies with a larger sample size are warranted to further explore these findings for mechanistic understanding and occupational policy consideration regarding stress risk reduction.