Cardiovascular Disease Risk In African Americans Research Articles

Abstract P170: Morning Surge and Cardiovascular Events in African Americans: The Jackson Heart Study

Introduction: A larger sleep-trough morning surge, defined as the mean two-hour post-awakening blood pressure (BP) minus the lowest asleep BP, has been associated with cardiovascular disease (CVD) events in Asians and Europeans. High asleep BP in African Americans (AA) may preclude a morning surge and an association with CVD due to a smaller BP change upon awakening. Objective: Determine the association of morning surge with CVD events in AAs. Methods: We analyzed participants from the Jackson Heart Study, a community-based cohort of AAs, with a complete 24-hour ambulatory BP monitoring recording and self-report asleep and awake times at baseline in 2000-2004 (n=767). Participants were grouped into tertiles of sleep-trough morning surge, two-hour post-awakening BP and lowest sleep BP. CVD events (nonfatal/fatal stroke, nonfatal myocardial infarction or fatal coronary heart disease; n=61) through December 2012 were adjudicated. Results: Participants’ mean age was 59.2 years and 32.1% were male. Multivariable adjusted hazard ratios (95% CI) for CVD events associated with Tertile 2 and 3 versus Tertile 1 of morning systolic BP (SBP) surge were 1.45 (0.71 – 2.97) and 2.03 (0.98 – 4.23), respectively; of post-awakening SBP were 2.01 (0.81 – 4.99) and 4.41 (1.85 – 10.50), respectively; and of lowest asleep SBP were 1.55 (0.68 – 3.52) and 2.22 (0.96 – 5.14), respectively ( Table ). Also, there was a graded increasing risk for CVD associated with Tertile 2 and 3 versus Tertile 1 of post-awakening diastolic BP (DBP), but not morning DBP surge and lowest asleep DBP. Conclusion: Higher morning SBP surge, post-awakening SBP and lowest asleep SBP and DBP were associated increased CVD risk in AAs.

Antioxidant intake in relation to serum C-reactive protein in mid-life and older African Americans

ABSTRACT Objective: African Americans (AAs) experience greater prevalence of cardiovascular disease (CVD) compared to other ethnic/racial groups. Low-grade chronic inflammation (often quantified by serum C-reactive protein CRP) is a well-documented risk factor for CVD. A healthy diet is plentiful in antioxidant nutrients and is associated with a lower inflammatory status and CVD risk. Our objective was to examine the relationship between dietary intake of antioxidants (carotenoids, vitamins A, C, E, and selenium) and serum CRP concentrations in mid-life and older AAs, while controlling for confounders. Methods: Data were from the baseline phase of a longitudinal church-based intervention study to reduce CVD risk in AAs. Anthropometrics were measured in a standard manner. Fasting serum samples were analyzed with ELISA for CRP. Multiple-pass 24-hour dietary recalls were used to assess intake; self-reported questionnaires were used to collect demographics. Statistical analyses were performed using SPSS Statistics 21 with the level of significance set at p < 0.05. Results: A total of n = 73 participants (n = 51 females) were included in the analyses. The females and males, respectively were 58.9 ± 10.3 and 59.4 ± 9.7 years old, with BMI of 34.6 ± 8.3 and 35.6 ± 9.3 kg/m2 (Mean ± SD). The mean serum CRP was above 0.6 mg/dL, although slightly lower in males. Males consumed more energy (kcal) and met RDA for selenium, whereas females met RDA for vitamin C. Both groups met RDA for vitamin A. All other dietary variables fell below the RDA or had no RDA established. Results from the binary logistic regression did not show significant association between dietary antioxidants and serum CRP in males or females. However, among females, for every unit increase in BMI, there was a 15% increase in serum CRP (OR = 1.15, p = 0.04). Conclusions: Our study does not support the inverse relationship between antioxidants intake and CRP, but does support the evidence for obesity-induced inflammation and suggests the association can be applied to AA women.

Leukocyte telomere length and cardiovascular disease in African Americans: The Jackson Heart Study

Background and aimsIn European descent populations, shorter leukocyte telomere length (LTL) has been associated with subclinical atherosclerosis, cardiovascular disease (CVD), and mortality, while longer LTL has been associated with greater left ventricular hypertrophy. We evaluated the relationship of LTL with subclinical cardiovascular disease indices and incident clinical events and mortality in African Americans (AAs). MethodsAnalyses were restricted to 2518 participants of the Jackson Heart Study (JHS) with LTL measured by Southern blot in baseline blood samples. ResultsAdjusting for established CVD risk factors, longer LTL was significantly associated with lower prevalence of coronary artery calcification (CAC) (odds ratio (OR) = 0.810) per 1 kb increase in LTL; (95% confidence interval [CI] 0.656, 0.9998), p=0.0498). Longer LTL was also associated with higher ankle brachial index (ABI) (β = 0.023; (95% CI 0.004, 0.042), p=0.017) when comparing the highest to the lowest LTL quartile. There were no significant associations between LTL and abdominal aortic calcification, carotid intima-media thickness, or left ventricular mass. After a median follow-up of 9 years, longer LTL was associated with lower risk of incident ischemic stroke (hazard ratio (HR) 0.69 (95% CI 0.48, 0.99), p=0.044) and total mortality (HR 0.81 (95% CI 0.67, 0.97), p=0.026) in age and sex adjusted models, but these associations were no longer significant in fully adjusted models. ConclusionsAmong a community-based cohort of AAs, longer LTL was nominally associated with lower odds of CAC and increased ABI, indicative of decreased prevalence of subclinical atherosclerosis and peripheral arterial disease. These findings do not offer strong support for LTL as an independent biomarker of CVD risk in AAs.

Abstract P180: A Racial Comparison of Vascular Hemodynamics in Middle-aged Americans: The Jackson Heart Study

Background: Despite the higher rates of hypertension and cardiovascular disease (CVD) sequela due to hypertension in African Americans (AA), literature on the hemodynamic factors contributing to vascular stiffness is sparse in this high risk population. Objective: We investigated the hemodynamics of vascular stiffness and its components in a middle-aged cohort of AA using arterial tonometry and compared findings to what has been seen in a healthy cohort of non-Hispanic whites from Framingham. Methods: Noninvasive hemodynamic factors were measured in 1,750 Jackson Heart Study participants (68±11 years, 65% female). A healthy reference group from published work in Framingham was used to determine the prevalence of abnormals in the Jackson Heart Study sample. Reference group was defined in Framingham as those with: age (&lt;50 years), blood pressure (BP, 140/90 mmHg), total cholesterol (&lt;200 mg/dL), body mass index (&lt;30 kg/m2), no diabetes, not currently smoking, and no history of CVD. Abnormal hemodynamic factors were defined as measurements outside the 95th or 5th percentile of the reference group. Using comparison of proportions, we determined the difference in abnormal prevalence rates between middle-aged AA in the Jackson Heart Study and non-Hispanic whites in Framingham. Results: The prevalence rates of abnormal hemodynamic variables in a middle-aged group of AA was compared to that seen in middle-aged non-Hispanic whites in Framingham using a published reference sample of normals in Framingham. Compared to non-Hispanic whites in Framingham, the prevalence of abnormals found in Jackson Heart Study AA was higher for diastolic BP (p=0.009), peripheral resistance (p&lt;0.001), characteristic impedance (p=0.006), carotid-brachial pulse wave velocity (p=0.038) and cardiac output (p&lt;0.001). Conclusion: Abnormalities in pulsatile hemodynamic variables are much more common (and severe) in AA than European Americans, which may contribute to higher CVD risk in AA.

Abstract 12: Socioeconomic Correlates of Cardiovascular Disease Risk in African Americans: The Jackson Heart Study

Background: Research has found that socioeconomic status (SES) is associated with cardiovascular disease (CVD) risk. However, few studies have reported the SES correlates of CVD risk in African Americans (AA). Since low SES is over-represented in AA, our objective is to examine the socioeconomic correlates of CVD risk in this population, which may provide new insights on racial/ethnic disparities in CVD risk. Methods: A cross-sectional analysis of baseline data collected in the Jackson Heart Study (JHS), an entirely AA population, was performed. Multivariable logistic regression analysis estimated the age and sex-adjusted association of SES indicators (education, household income and occupation) with prevalent CVD (myocardial infarction (MI), stroke and hypertension). Stratified analyses by age (&lt;65 and ≥65 years) and sex were also performed. Additional analyses were performed using logistic models with a backward selection procedure that included age, sex, education, household income, occupation and burden of CVD risk factors (measured by the number of Life’s Simple 7® metrics meeting ideal health) as independent variables and prevalent CVD as dependent variables, Due to missing data, sample sizes for these analyses ranged from 3,473 to 5,301. Results: Baseline prevalence for MI, stroke and hypertension were 5.5%, 4.4% and 60.1%. About one-third (32.5%) of the participants had a bachelor’s degree, 35% held management or professional occupations and 30% were “affluent” (≥3.5 US Census poverty level). We observed an inverse relationship between prevalent CVD and SES indicators. The largest and most consistent SES correlate of prevalent CVD was observed with income on MI (odds ratio (OR) 3.5; 95% CI 2.3, 5.4) and stroke (OR 3.7; 95% CI 2.3, 6.0) comparing the poor (below US Census poverty level) to the affluent income categories. Stratified analyses suggested stronger SES gradients in individuals &lt;65 years and in females for MI. In the backward logistic regression models, the significant SES indicators (p&lt;0.05) remaining in the final model were income for MI and stroke, and occupation for hypertension. The burden of CVD risk factors was statistically significant and remained in the final model for all three CVD outcomes. Conclusions: Inverse SES gradients on the prevalence of MI, stroke and hypertension were observed among AA in the JHS. The most important SES correlates were income for MI and stroke, and occupation for hypertension. These findings suggest SES, and income in particular, is an important factor contributing to health disparities in CVD among AA and possibly AA-White disparities in health outcomes.

Abstract P264: Association of D-dimer with Incident Cardiovascular Disease Events and F3 Gene Variants in African Americans: Results From the Jackson Heart Study

Plasma D-dimer, a fibrin degradation product, is a biomarker of both coagulation and fibrinolysis and a risk factor for both arterial and venous thrombosis. African Americans (AAs) have increased risk of thrombosis and higher levels of D-dimer as compared to European populations, but little is known about the genetic architecture of D-dimer in AAs. D-dimer was assessed in 4163 AAs from the Jackson Heart Study (mean age 55 years, 62.1% female). We hypothesized that D-dimer levels would associate with incident cardiovascular disease events and with both coding and noncoding genetic variants. Median (interquartile range) D-dimer in the cohort was 0.40 (0.26-0.64) μg/ml. D-dimer was associated with increased risk of coronary heart disease (hazard ratio (HR) per standard deviation (SD)=1.26, p=0.012), stroke (HR=1.27, p=0.018), heart failure (HR=1.33, p=0.001), and mortality (HR=1.25, p&lt;0.0001) in models adjusted for age, sex, BMI, current smoking, diabetes, hypertension, systolic blood pressure, and low-density lipoprotein cholesterol. Using data from the Affymetrix Genome-Wide Human SNP Array 6.0, imputation based on the 1000 Genomes project reference panel (Phase I, Version 3, March 2012 release) was completed using MACH 1.0 and minimac in 2709 participants with D-dimer. Associations were assessed using MACH2QTL v.1.13, with models adjusted for age, sex, and the first ten principal components for global ancestry calculated using EIGENSOFT. The most significant signal was for an intergenic locus near F3 (top variant rs2022030, p=5.71x10 -12 , minor allele frequency=10.6%, imputation r 2 =1). F3 codes for tissue factor, a necessary co-factor for factor VIIa in the initiation of the extrinsic blood coagulation pathway. The F3 locus had been previously associated with D-dimer levels in European populations but has not been reported for AAs. Data were also available from the Illumina HumanExome Beadchip, version 1.1, in 2502 individuals; single variant analyses and gene-based tests for nonsynonymous, splicing, and nonsense variants with a minor allele frequency &lt;5% were performed using RAREMETAL, adjusted for age, sex, and the first ten principal components. For single variant analyses, a nonsynonymous variant in GPRASP1 (G protein-coupled receptor associated sorting protein 1, rs145805077, p= 1.84x10 -7 , minor allele frequency=0.3%) was significantly associated with decreased D-dimer. No gene-based test result met the strict multiple comparison significance threshold; the top gene-based result with the sequence kernel association test (SKAT) was for six variants in PPM1M (protein phosphatase, Mg2+/Mn2+ dependent, 1M, p=6.09x10 -6 ). These results highlight D-dimer as an important predictor of cardiovascular disease risk in AAs and that levels of this biomarker are associated with the F3 locus.

Abstract MP65: Masked Hypertension is Associated with Cardiovascular Disease Events in African Americans: The Jackson Heart Study

Introduction: Masked hypertension has been associated with increased cardiovascular disease (CVD) risk in Europeans and Asians. Hypothesis: Determine the association of masked hypertension with CVD events and all-cause mortality in African Americans (AA). Methods: The Jackson Heart Study, an exclusively AA population-based, prospective cohort study, was restricted to participants with clinic systolic/diastolic blood pressure (SBP/DBP) &lt; 140/90 mmHg and valid ambulatory blood pressure monitoring (ABPM) at the baseline exam in 2000-2004 (n=738). Masked daytime hypertension was defined as mean ambulatory daytime (10am-8pm) SBP ≥ 135 mmHg or DBP ≥ 85 mmHg. Masked nocturnal hypertension was defined as mean ambulatory nighttime (12am-6am) SBP ≥ 120 mmHg or DBP ≥ 70 mmHg. Using all ABPM measurements, masked 24-hour hypertension was defined as mean SBP ≥ 130 mmHg or DBP ≥ 80 mmHg. CVD events (nonfatal/fatal stroke, nonfatal myocardial infarction or fatal coronary heart disease) and all-cause mortality were identified and adjudicated through December 31, 2011. Results: Any masked hypertension (masked daytime, nocturnal or 24-hour hypertension) was present in 52.2% of participants; 28.2% had masked daytime hypertension, 48.2% had masked nocturnal hypertension and 31.7% had masked 24-hour hypertension. There were 51 CVD events and 44 deaths over a median follow up of 8.2 and 8.5 years, respectively. The CVD rate (95% CI) per 1,000 person years in participants with and without any masked hypertension were 13.5 (9.9-18.4) and 3.9 (2.2-7.1), respectively (Table). The multivariable adjusted hazard ratio (95% CI) between any masked hypertension and CVD was 2.49 (1.26-4.93). CVD rates for those with and without masked daytime, nocturnal and 24-hour hypertension, and the hazard ratios for CVD associated with masked daytime, nocturnal and 24-hour hypertension, were similar. Masked hypertension was not associated with all-cause mortality. Conclusion: Masked hypertension is common and associated with increased CVD risk in AAs.

Sex Differences in Associations of Depressive Symptoms with Cardiovascular Risk Factors and Metabolic Syndrome among African Americans.

Young to middle-aged women usually have notably lower rates of cardiovascular disease (CVD) than their male counterparts, but African American women lack this advantage. Their elevated CVD may be influenced by sex differences in associations between depressed mood and CVD risk factors. This cross-sectional study examined whether relations between scores on the Center for Epidemiologic Studies-Depression (CES-D) scale and a spectrum of CVD risk factors varied by sex among African Americans (n = 1076; ages 30–64) from the Healthy Aging in Neighborhoods of Diversity across the Life Span (HANDLS) study. Sex-stratified multiple regressions and logistic regressions were conducted. Among women, CES-D scores correlated positively with systolic blood pressure and waist-to-hip ratio (P's < .05), but inversely with high-density lipoprotein cholesterol (HDL-C) (P < .01). Women had twice the odds for metabolic syndrome if CES-D scores ≥16 and had a ≥14% increase in odds of hypertension, abdominal obesity, and low HDL-C with each 5-unit increase in CES-D scores. Among men, CES-D scores correlated positively with high-sensitivity C-reactive protein (P < .05), and odds of hypertension increased by 21% with each 5-unit increase in CES-D scores. Depressive symptoms may promote premature CVD risk in African Americans, at least in part, via CVD risk factors and prevalent metabolic syndrome, particularly in African American women.

Jackson Heart Study: A Perspective at Ten Years

The Jackson Heart Study was established with the goal of reversing the epidemic of cardiovascular disease (CVD) in African Americans. CVD, encompassing both heart disease and stroke, is the leading cause of death and disability in the United States, and the CVD rate is higher in African Americans than whites. The prevalence of CVD is 45% in African American men, 47% in African American women, 38% in white men, and 34% in white women [1]. The disproportionately high rate of CVD in African Americans occurs even when socioeconomic and health insurance status are similar [2, 3]. To elucidate the reasons for the high CVD rate in African Americans, The Jackson Heart Study, modeled after the landmark Framingham Heart Study, was established. In 1948, the Framingham Heart Study began in Framingham, MA with the random enrollment of two thirds of the residents in this eastern Massachusetts town. The original cohort consisted of 5,209 men and women. More than 98% of the participants were white. The cohort was evaluated prospectively, and subsequent generations were added: the Offspring cohort in 1971 and the Third Generation cohort in 2002 (http://www.framinghamheartstudy.org). From this extensive, prospective, multigenerational database, clear and convincing evidence of the dangers of high blood pressure, high blood cholesterol, and smoking were established. Therefore, data from the Framingham Heart Study has had a significant impact on health and environmental policy in the United States. In addition, using the original and offspring cohorts, a risk score for the prediction of CVD has been established and is known as the Framingham Risk Score [4]. Yet, even with the Framingham Risk Score, CVD mortality remains significantly higher in African Americans than whites. Hence, the need for a longitudinal study of CVD specifically focused on African Americans is clear. To evaluate the epidemiology and pathophysiology of cardiovascular risk and disease in African Americans, the Jackson Heart Study began in 2000 in Jackson, MS. For several reasons, Jackson was an ideal location for a prospective study of CVD risk in African Americans. Mississippi has the highest rate of CVD in the nation [1]. Additionally, the African American community in Jackson was familiar with participation in prospective studies of CVD risk. Jackson residents had previously participated in the Atherosclerosis Risk in Communities (ARIC) study. The ARIC study was an investigation of the causes and progression of atherosclerosis. African Americans enrolled in ARIC were specifically recruited from Jackson. Therefore, from 1987 to 1988, 3,732 African Americans from Jackson aged 45 to 64 years participated in ARIC [5, 6]. The ARIC study not only established Jackson as a high-risk community, but also exposed the community to the benefits of clinical research. Therefore, the National Heart, Lung, and Blood Institute (NHLBI) and the National Institute for Minority Health and Health Disparities (NIMHD) chose Jackson as the site for the major prospective study of CVD in African Americans. The Jackson Heart Study was structured as a partnership between three institutions in Mississippi: the University of Mississippi Medical Center, Jackson State University, and Tougaloo College, with funding and active guidance from the NHLBI and NIMHD [7].

The Cholesterol, Hypertension, and Glucose Education (CHANGE) study for African Americans with diabetes: Study design and methodology

Cardiovascular disease (CVD) and diabetes account for over one third of the mortality difference between African Americans and white patients. The increased CVD risk in African Americans is due in large part to the clustering of multiple CVD risk factors. The current study is aimed at improving CVD outcomes in African-American adults with diabetes by addressing the modifiable risk factors of systolic blood pressure , glycosylated hemoglobin, and low-density lipoprotein cholesterol. A sample of African American patients with diabetes (N = 400) will receive written education material at baseline and be randomized to one of 2 arms: (1) usual primary care or (2) nurse-administered disease-management intervention combining patient self-management support and provider medication management. The nurse administered intervention is delivered monthly over the telephone. The nurses also interacts with the primary care providers at 3, 6, and 9 months to provide concise patient updates and facilitate changes in medical management. All patients are followed for 12 months after enrollment. The primary outcomes are change in glycosylated hemoglobin, systolic blood pressure, and low-density lipoprotein cholesterol over 12-months. Secondary outcomes include change in overall cardiovascular risk, aspirin use, and health behaviors. Given the continued racial disparities in CVD, the proposed study could result in significant contributions to cardiovascular risk reduction in African-American patients.