Issues in minority health: atherosclerosis and coronary heart disease in African Americans

Abdominal Compared With Coronary Artery Calcification and Incident Cardiovascular Events and Mortality in Black Adults

BACKGROUND

Black adults show heightened cardiovascular risk compared with other groups despite comparable or lower coronary artery calcium (CAC) scores, indicating potential cardiovascular risk underestimation by CAC. Abdominal aortic calcification (AAC), preceding CAC, may predict cardiovascular events better in Black adults who are prone to early atherosclerotic cardiovascular disease and excess events at low CAC scores.

METHODS

We included 2551 participants from the JHS (Jackson Heart Study) visit 2 examination (2005-2008) without cardiovascular disease, followed through 2016. Cox regression estimated hazard ratios for incident cardiovascular events defined as a composite of myocardial infarction, stroke, heart failure, and all-cause mortality. The predictive value of CAC and AAC, when added to the American College of Cardiology/American Heart Association cardiovascular risk algorithm (pool cohort equation), was assessed.

RESULTS

Mean age was 57±10 years; 66% were women. Over a follow-up period of 12.6 years, 287 (11.3%) cardiovascular events and 360 (14.1%) mortality cases were observed. Adjusting for demographic and clinical variables, each 2-fold increase in CAC and AAC was associated with cardiovascular events (CAC: hazard ratio, 1.10 [95% CI, 1.06-1.13]; AAC: hazard ratio, 1.10 [95% CI, 1.06-1.13]) and all-cause mortality CAC: hazard ratio, 1.04 [95% CI, 1.01-1.08]; AAC: hazard ratio, 1.05 [95% CI, 1.01-1.08]). The incremental value of CAC (0.17 [95% CI, 0.08-0.23]) and AAC (0.15 [95% CI, 0.07-0.29]) to the pool cohort equation by net reclassification index was comparable. Notably, 45% of participants with 0 CAC showed some degree of AAC. Each 2-fold increase in AAC was associated with an increased risk of cardiovascular events (hazard ratio, 1.07 [95% CI, 1.01-1.19]) but not all-cause mortality among participants with 0 CAC.

CONCLUSIONS

AAC is comparable to CAC in predicting cardiovascular events and all-cause mortality among Black adults, potentially valuable when CAC is absent.

Proteomic changes associated with racial background and sepsis survival outcomes

Intra-abdominal infection is a common cause of sepsis, and intra-abdominal sepsis leads to ∼156 000 U.S. deaths annually. African American/Black adults have higher incidence and mortality rates from sepsis compared to Non-Hispanic White adults. A limited number of studies have traced survival outcomes to molecular changes; however, these studies primarily only included Non-Hispanic White adults. Our goal is to better understand molecular changes that may contribute to differences in sepsis survival in African American/Black and Non-Hispanic White adults with primary intra-abdominal infection. We employed discovery-based plasma proteomics of patient samples from the Protocolized Care for Early Septic Shock (ProCESS) cohort (N = 107). We identified 49 proteins involved in the acute phase response and complement system whose expression levels are associated with both survival outcome and racial background. Additionally, 82 proteins differentially-expressed in survivors were specific to African American/Black or Non-Hispanic White patients, suggesting molecular-level heterogeneity in sepsis patients in key inflammatory pathways. A smaller, robust set of 19 proteins were in common in African American/Black and Non-Hispanic White survivors and may represent potential universal molecular changes in sepsis. Overall, this study identifies molecular factors that may contribute to differences in survival outcomes in African American/Black patients that are not fully explained by socioeconomic or other non-biological factors.

Risk of Myocardial Infarction in Inflammatory Bowel Disease: A Population-based National Study

BACKGROUND & OBJECTIVE

Chronic inflammation is linked to increased cardiovascular risk. Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract and elevated pro-inflammatory markers. The association between IBD and myocardial infarction (MI) is not well understood. We sought to elucidate this risk using a large database.

METHODS

We reviewed data from a large commercial database (Explorys, IBM Watson) that aggregates electronic medical records from 26 nationwide health care systems. Using systemized nomenclature of medicine-clinical terms, we identified adult patients (20 to 65 years) with a diagnosis of IBD-ulcerative colitis (UC) or Crohn's disease (CD)-who had active records between August 2013 and August 2018. We then examined the risk of MI in patients with or without IBD.

RESULTS

Out of 29,090,220 patients, 131,680 (0.45%) had UC, and 158,750 (0.55%) had CD. Prevalence of MI was higher in patients with UC and CD versus non-IBD patients (UC 6.7% vs CD 8.8% vs non-IBD 3.3%, odds ratio [OR] for UC 2.09 [2.04 -2.13], and CD 2.79 [2.74-2.85]. The odds of MI in IBD patients overall were highest in younger patients and decreased with age (age 30-34 years: OR 12.05 [11.16-13.01], age 65+ years: OR 2.08 [2.04-2.11]). After adjusting for age, race, sex, and traditional cardiovascular risk factor, IBD conferred greater odds of MI (adjusted odds ratio [aOR] 1.25 [1.24-1.27]).

CONCLUSION

In this large cohort, IBD is associated with significantly increased MI compared with non-IBD patients. The relative risk of MI was highest in younger patients and decreased with age. These findings emphasize the need for aggressive risk factor reduction in IBD.

Nonhematopoietic Nrf2 dominantly impedes adult progression of sickle cell anemia in mice

The prevention of organ damage and early death in young adults is a major clinical concern in sickle cell disease (SCD). However, mechanisms that control adult progression of SCD during the transition from adolescence are poorly defined with no cognate prophylaxis. Here, we demonstrate in a longitudinal cohort of homozygous SCD (SS) mice a link between intravascular hemolysis, vascular inflammation, lung injury, and early death. Prophylactic Nrf2 activation in young SS mice stabilized intravascular hemolysis, reversed vascular inflammation, and attenuated lung edema in adulthood. Enhanced Nrf2 activation in endothelial cells in vitro concurred with the dramatic effect on vascular inflammation in the mice. BM chimeric SS mice lacking Nrf2 expression in nonhematopoietic tissues were created to dissect the role of nonerythroid Nrf2 in SCD progression. The SS chimeras developed severe intravascular hemolysis despite having erythroid Nrf2. In addition, they developed premature vascular inflammation and pulmonary edema and died younger than donor littermates with intact nonhematopoietic Nrf2. Our results reveal a dominant protective role for nonhematopoietic Nrf2 against tissue damage in both erythroid and nonerythroid tissues in SCD. Furthermore, we show that prophylactic augmentation of Nrf2-coordinated cytoprotection effectively impedes onset of the severe adult phenotype of SCD in mice.

Health Behavior Decision-making in African-American Adults Diagnosed with Schizophrenia

Little is known about the factors that influence health behavior decision-making among people with schizophrenia. The purpose of this qualitative study was to describe the processes used by 10 African-American adults with schizophrenia when making health behavior decisions and identification of perceived barriers and facilitators to health. Three phases of health behavior decision-making were identified: Recognizing Complex Components of Health, Personalizing Components of Health, and Tracking Health Status. Findings may guide clinicians' efforts to improve the health status of patients, as well as influence future research in understanding health behavior decision-making among vulnerable populations.

Stratified patient-centered care in type 2 diabetes: a cluster-randomized, controlled clinical trial of effectiveness and cost-effectiveness

OBJECTIVE

Diabetes treatment should be effective and cost-effective. HbA1c-associated complications are costly. Would patient-centered care be more (cost-) effective if it was targeted to patients within specific HbA1c ranges?

RESEARCH DESIGN AND METHODS

This prospective, cluster-randomized, controlled trial involved 13 hospitals (clusters) in the Netherlands and 506 patients with type 2 diabetes randomized to patient-centered (n=237) or usual care (controls) (n=269). Primary outcomes were change in HbA1c and quality-adjusted life years (QALYs); costs and incremental costs (USD) after 1 year were secondary outcomes. We applied nonparametric bootstrapping and probabilistic modeling over a lifetime using a validated Dutch model. The baseline HbA1c strata were <7.0% (53 mmol/mol), 7.0-8.5%, and >8.5% (69 mmol/mol).

RESULTS

Patient-centered care was most effective and cost-effective in those with baseline HbA1c>8.5% (69 mmol/mol). After 1 year, the HbA1c reduction was 0.83% (95% CI 0.81-0.84%) (6.7 mmol/mol [6.5-6.8]), and the incremental cost-effectiveness ratio (ICER) was 261 USD (235-288) per QALY. Over a lifetime, 0.54 QALYs (0.30-0.78) were gained at a cost of 3,482 USD (2,706-4,258); ICER 6,443 USD/QALY (3,199-9,686). For baseline HbA1c 7.0-8.5% (53-69 mmol/mol), 0.24 QALY (0.07-0.41) was gained at a cost of 4,731 USD (4,259-5,205); ICER 20,086 USD (5,979-34,193). Care was not cost-effective for patients at a baseline HbA1c<7.0% (53 mmol/mol).

CONCLUSIONS

Patient-centered care is more valuable when targeted to patients with HbA1c>8.5% (69 mmol/mol), confirming clinical intuition. The findings support treatment in those with baseline HbA1c 7-8.5% (53-69 mmol/mol) and demonstrate little to no benefit among those with HbA1c<7% (53 mmol/mol). Further studies should assess different HbA1c strata and additional risk profiles to account for heterogeneity among patients.

Associations between metabolomic compounds and incident heart failure among African Americans: the ARIC Study

Heart failure is more prevalent among African Americans than in the general population. Metabolomic studies among African Americans may efficiently identify novel biomarkers of heart failure. We used untargeted methods to measure 204 stable serum metabolites and evaluated their associations with incident heart failure hospitalization (n = 276) after a median follow-up of 20 years (1987-2008) by using Cox regression in data from 1,744 African Americans aged 45-64 years without heart failure at baseline from the Jackson, Mississippi, field center of the Atherosclerosis Risk in Communities (ARIC) Study. After adjustment for established risk factors, we found that 16 metabolites (6 named with known structural identities and 10 unnamed with unknown structural identities, the latter denoted by using the format X-12345) were associated with incident heart failure (P < 0.0004 based on a modified Bonferroni procedure). Of the 6 named metabolites, 4 are involved in amino acid metabolism, 1 (prolylhydroxyproline) is a dipeptide, and 1 (erythritol) is a sugar alcohol. After additional adjustment for kidney function, 2 metabolites remained associated with incident heart failure (for metabolite X-11308, hazard ratio = 0.75, 95% confidence interval: 0.65, 0.86; for metabolite X-11787, hazard ratio = 1.23, 95% confidence interval: 1.10, 1.37). Further structural analysis revealed X-11308 to be a dihydroxy docosatrienoic acid and X-11787 to be an isoform of either hydroxyleucine or hydroxyisoleucine. Our metabolomic analysis revealed novel biomarkers associated with incident heart failure independent of traditional risk factors.

Genetic variants in platelet factor 4 modulate inflammatory and platelet activation biomarkers

BACKGROUND

African Americans suffer from higher prevalence and severity of atherosclerosis compared with whites, highlighting racial and ethnic disparities in cardiovascular disease. Previous studies have pointed to the role of vascular inflammation and platelet activation in the formation of atherosclerotic lesions.

METHODS AND RESULTS

We explored the role of genetic variation in 4 chemokine/chemokine receptor genes (CX3CR1, CX3CL1, CXCR3, and PF4) on systemic inflammation and platelet activation serum biomarkers (fractalkine, platelet P-selectin, platelet factor 4 [PF4], and tumor necrosis factor-α). In total, 110 single nucleotide polymorphisms were tested among 1042 African Americans and 763 whites. The strongest association with serum PF4 levels was observed for rs168449, which was significant in both racial groups (P value: African Americans=0.0017, whites=0.014, combined=1.2 × 10(-4)), and remained significant after permutation-based multiple corrections (P(c) value: combined=0.0013). After accounting for the effect of rs168449, we identified another significant single nucleotide polymorphism (rs1435520), suggesting a second independent signal regulating serum PF4 levels (conditional P value: African Americans=0.02, whites=0.02). Together, these single nucleotide polymorphisms explained 0.98% and 1.23% of serum PF4 variance in African Americans and whites, respectively. Additionally, in African Americans, we found an additional PF4 variant (rs8180167), uncorrelated with rs168449 and rs1435520, associated with serum tumor necrosis factor-α levels (P=0.008, P(c)=0.048).

CONCLUSIONS

Our study highlights the importance of PF4 variants in the regulation of platelet activation (PF4) and systemic inflammation (tumor necrosis factor-α) serum biomarkers.

High Prevalence of Hypertension and Other Cardiometabolic Risk Factors in US- and Caribbean-Born Blacks with Chest Pain Syndromes

BACKGROUND: Caribbean-born blacks (CBB) have been reported to have lower coronary artery disease mortality rates than US-born blacks (UBB). We assessed whether CBB have a lower prevalence of cardiometabolic risk factors compared to UBB. METHODS: Non-Hispanic blacks (n = 275) hospitalized for chest pain who were prospectively enrolled in our Cardiovascular Outcomes Research Group (CORG) study provided clinical and demographic data. RESULTS: The study cohort comprised 45% (n = 125) UBB with a mean age of 61 ± 16 years and 55% (n = 150) CBB with a mean age of 63 ± 11 years. Myocardial infarction was diagnosed in 33% of UBB and 36% of CBB. CBB had a lower rate of previous myocardial infarction (14 vs. 24%; p = 0.04). They also smoked less (16 vs. 35%; p = 0.001) and were less likely to have first-degree relatives with coronary artery disease (24 vs. 41%; p = 0.018). However, they had a similarly high prevalence of hypertension (99 vs. 98%; p = 0.99), diabetes (58 vs. 48%; p = 0.11), dyslipidemia (53 vs. 42%; p = 0.08), and obesity (34 vs. 40%; p = 0.29) as UBB. CONCLUSION: A very high prevalence of hypertension exists in non-Hispanic blacks hospitalized for chest pain. CBB and UBB have a similar prevalence of cardiometabolic profile in our study population. Besides smoking, other factors contributing to lower CHD mortality reported for CBB need to be further explored.

Genome-wide association analysis of incident coronary heart disease (CHD) in African Americans: a short report

African Americans have the highest rate of mortality due to coronary heart disease (CHD). Although multiple loci have been identified influencing CHD risk in European-Americans using a genome-wide association (GWAS) approach, no GWAS of incident CHD has been reported for African Americans. We performed a GWAS for incident CHD events collected during 19 years of follow-up in 2,905 African Americans from the Atherosclerosis Risk in Communities (ARIC) study. We identified a genome-wide significant SNP (rs1859023, MAF = 31%) located at 7q21 near the PFTK1 gene (HR = 0.57, 95% CI 0.46 to 0.69, p = 1.86×10⁻⁰⁸), which replicated in an independent sample of over 8,000 African American women from the Women's Health Initiative (WHI) (HR = 0.81, 95% CI 0.70 to 0.93, p = 0.005). PFTK1 encodes a serine/threonine-protein kinase, PFTAIRE-1, that acts as a cyclin-dependent kinase regulating cell cycle progression and cell proliferation. This is the first finding of incident CHD locus identified by GWAS in African Americans.

In the United States, African Americans are at high risk for coronary heart disease (CHD). Although environmental and social factors have a role, genetic factors also contribute to CHD risk and mortality. Research to identify genetic factors for CHD susceptibility has been carried out mostly in Europeans and European Americans and little has been done in African Americans. Genome wide association studies (GWAS) provide a means to identify susceptibility loci without any a priori assumptions about the functional importance of a gene. In this study, we used GWAS to identify a novel genomic region associated with incident CHD events in African Americans from the ARIC study and replicated this finding in a large sample of African American women. This region contains several genes, including PFTK1, that regulate cell cycle progression and cell proliferation. This is the first report of a susceptibility locus for incident CHD identified by GWAS in African Americans.

Risk of coronary heart disease events over 15 years among older adults with depressive symptoms

OBJECTIVES

To determine whether depression status is associated with an increased risk of coronary heart disease (CHD) events, defined as CHD death or nonfatal acute myocardial infarction (MI).

DESIGN

Prospective cohort study.

SETTING

An urban primary care practice.

PARTICIPANTS

Two thousand seven hundred twenty-eight adults (71.4% women, 65.5% black), age 60 years and older, who were screened for depression between 1991 and 1993.

MEASUREMENTS

Depressive symptom severity at baseline was assessed by the Center for Epidemiologic Studies Depression Scale (CES-D). Data regarding baseline demographic and clinical variables, as well as laboratory evidence of acute MI, were obtained from an electronic medical record system. All-cause mortality and CHD death were determined from the National Death Index through 2006.

RESULTS

A total of 423 (15.5%) participants reported elevated symptoms of depression (CES-D score ≥16). During the 13 to 16 years of follow-up, 1,646 (60.3%) individuals died from any cause, and 727 (26.6%) died from CHD or suffered an acute MI. Cox proportional hazards models revealed that individuals with elevated depressive symptoms were more likely to experience a CHD event, even after adjustment for demographics and comorbid health conditions (relative risk = 1.46, 95% confidence interval: 1.20-1.77). Depression status was also a significant predictor of all-cause mortality in adjusted models.

CONCLUSIONS

We report the longest prospective study to date to examine depression status as an independent risk factor for CHD among a cohort of older adults including large numbers of women and underrepresented minorities. The present findings underscore the need to consider depression as a common and modifiable risk factor for CHD events among older adults.

Disparities in amputations in minorities

BACKGROUND

As a result of the impact of health disparities on the healthcare system such as their influence on arenas significant to healthcare distribution, including cost, quality, and access, identification and resolution of health disparities is a primary national agenda item. Resolution of disparities in amputation is an area of opportunity that warrants further consideration.

QUESTIONS/PURPOSES

The purposes of our review are to highlight current data on disparities in amputation in minorities and to consider future goals related to an elimination of this disparity.

METHODS

Studies on disparities in amputation were accessed using the following databases: PubMed, Cinahl, OVID/Medline, Embase, and Cochrane databases. In each database, a search of title/abstract was performed for the search terms "disparities and amputation," "race and amputation," and "diabetes and amputation." Each search was limited by human and English language. Where are we now? A disparity exists in both frequency and level of amputation in minorities both in the presence and absence of a diagnosis of diabetes. Where do we need to go? A need exists for future research involving a more deliberate examination of the use of preventive screening for patients at high risk for amputation across medical settings. How do we get there? Research in this area would benefit from funding, large-scale data collection, and physician exposure to education on high-risk patients and preventive screening opportunities.

The GoodNEWS (Genes, Nutrition, Exercise, Wellness, and Spiritual Growth) Trial: a community-based participatory research (CBPR) trial with African-American church congregations for reducing cardiovascular disease risk factors--recruitment, measurement, and randomization

INTRODUCTION

Although cardiovascular diseases (CVD) are the leading cause of death among Americans, significant disparities persist in CVD prevalence, morbidity, and mortality based on race and ethnicity. However, few studies have examined risk factor reduction among the poor and ethnic minorities.

METHODS

Community-based participatory research (CBPR) study using a cluster randomized design--African-American church congregations are the units of randomization and individuals within the congregations are the units of analysis. Outcome variables include dietary change (Diet History Questionnaire), level of physical activity (7-Day Physical Activity Recall), lipoprotein levels, blood pressure, fasting glucose, and hemoglobin A1c.

RESULTS

Eighteen (18) church congregations were randomized to either a health maintenance intervention or a control condition. Complete data were obtained on 392 African-American individuals, 18 to 70 years of age, predominantly employed women with more than a high school diploma. Treatment and intervention groups were similar at baseline on saturated fat intake, metabolic equivalent of tasks (METS) per day, and other risk factors for CVD.

CONCLUSIONS

The GoodNEWS trial successfully recruited and evaluated CVD-related risk among African-American participants using a CBPR approach. Several logistical challenges resulted in extending the recruitment, preliminary training, and measurement periods. The challenges were overcome with the assistance of a local community consultant and a professional event planner. Our experience supports the need for incorporating non-traditional community-based staff into the design and operational plan of CBPR trials.

The contribution of hypertension to black-white differences in likelihood of coronary artery disease detected during elective angiography

BACKGROUND

Black patients in the United States undergoing angiography for suspected coronary artery disease (CAD) have consistently been found to have less disease than whites. As the effects of hypertension are greater in blacks than whites, and hypertensive heart disease may mimic CAD and lead to catheterization, we examined the association between race and hypertension as an explanation for the disparities in angiographic CAD.

METHODS

Using an academic hospital's institutional database, we studied patients undergoing first-time elective angiography from 2001 to 2008. Using multivariable logistic regression with data on patient demographics, CAD risk factors, and coronary stenoses, we compared rates of angiographic disease for blacks and whites, creating models separately for patients with and without hypertension. We then tested the significance of an interaction term between race and hypertension on angiographic findings.

RESULTS

We identified 1,203 black and 2,538 white patients who underwent initial elective angiography. Black patients were less likely to have a significant stenotic lesion (≥50% stenosis in the left main artery or ≥70% stenosis elsewhere) than whites (adjusted risk ratio 0.65; 95% confidence interval (CI) 0.55-0.75). Among patients with hypertension this difference was exaggerated (adjusted risk ratio 0.60; 95% CI 0.51-0.71). However, among patients without hypertension, the risk of having a significant lesion was similar in blacks and whites (adjusted risk ratio 0.97; 95% CI 0.67-1.37). The interaction term for race and hypertension was confirmed as statistically significant.

CONCLUSIONS

Among patients electively referred for angiography, hypertension, and its effects may contribute to the lower rate of CAD found in blacks compared to whites.

Differential endothelial cell gene expression by African Americans versus Caucasian Americans: a possible contribution to health disparity in vascular disease and cancer

BACKGROUND

Health disparities and the high prevalence of cardiovascular disease continue to be perplexing worldwide health challenges. This study addresses the possibility that genetic differences affecting the biology of the vascular endothelium could be a factor contributing to the increased burden of cardiovascular disease and cancer among African Americans (AA) compared to Caucasian Americans (CA).

METHODS

From self-identified, healthy, 20 to 29-year-old AA (n = 21) and CA (n = 17), we established cultures of blood outgrowth endothelial cells (BOEC) and applied microarray profiling. BOEC have never been exposed to in vivo influences, and their gene expression reflects culture conditions (meticulously controlled) and donor genetics. Significance Analysis of Microarray identified differential expression of single genes. Gene Set Enrichment Analysis examined expression of pre-determined gene sets that survey nine biological systems relevant to endothelial biology.

RESULTS

At the highly stringent threshold of False Discovery Rate (FDR) = 0, 31 single genes were differentially expressed in AA. PSPH exhibited the greatest fold-change (AA > CA), but this was entirely accounted for by a homolog (PSPHL) hidden within the PSPH probe set. Among other significantly different genes were: for AA > CA, SOS1, AMFR, FGFR3; and for AA < CA, ARVCF, BIN3, EIF4B. Many more (221 transcripts for 204 genes) were differentially expressed at the less stringent threshold of FDR <.05. Using the biological systems approach, we identified shear response biology as being significantly different for AA versus CA, showing an apparent tonic increase of expression (AA > CA) for 46/157 genes within that system.

CONCLUSIONS

Many of the genes implicated here have substantial roles in endothelial biology. Shear stress response, a critical regulator of endothelial function and vascular homeostasis, may be different between AA and CA. These results potentially have direct implications for the role of endothelial cells in vascular disease (hypertension, stroke) and cancer (via angiogenesis). Also, they are consistent with our over-arching hypothesis that genetic influences stemming from ancestral continent-of-origin could impact upon endothelial cell biology and thereby contribute to disparity of vascular-related disease burden among AA. The method used here could be productively employed to bridge the gap between information from structural genomics (for example, disease association) and cell function and pathophysiology.

Reaching individuals at risk for cardiovascular disease through community outreach in Colorado

OBJECTIVE

The aim of this program was to (1) increase awareness of individual cardiovascular disease (CVD) risk in underserved communities, (2) educate participants about lifestyle modifications to reduce CVD risk, and (3) link individuals at moderate to high risk with healthcare. Community health workers (CHWs) delivered the program in 14 urban, rural and frontier Colorado communities.

METHOD

We analyzed data from CVD screenings of 17,995 individuals throughout Colorado between 2006 and 2009 in order to understand the reach and impact of the program on reaching target populations, identifying at-risk individuals and improving awareness of CVD risk.

RESULTS

In 3 years, 15 CHWs screened 17,995 clients for CVD risk, of which, almost 60% were racial and ethnic minorities and 42% were uninsured. Twenty-nine percent of participants had medium or high Framingham Risk Scores. Over three-quarters were overweight or obese, over one-fifth had mildly to severely high blood pressure, and 42% had borderline high or high cholesterol. Significantly, 82% had no knowledge of their CVD risk prior to screening.

CONCLUSION

This program is a replicable model for reaching minority and medically underserved populations who are at risk for CVD in urban, rural and frontier communities.

Risk factor profiles for atherosclerotic cardiovascular disease in black and other Africans with established rheumatoid arthritis

OBJECTIVE

Black Africans reportedly experience a distinctly low risk for atherosclerotic cardiovascular disease (CVD). We investigated whether this protection was present among Africans with established rheumatoid arthritis (RA).

METHODS

We determined disparities in CVD risk factor profiles (major conventional: hypertension, dyslipidemia, smoking, and diabetes; other conventional: underweight, obesity, metabolic syndrome, chronic kidney disease, alcohol consumption, tension, depression, and body height; nonconventional: rheumatoid factor status and markers of inflammation) and arterial stiffness (brachial pulse pressure) between 291 black and 335 other (229 white, 64 Asian, and 42 mixed ancestry) consecutive Africans with RA in multivariable regression models.

RESULTS

After adjusting for demographic characteristics and healthcare sector attendance, black Africans had more prevalent hypertension (OR 1.76, p = 0.01) and diabetes (OR 1.90, p = 0.07), smoked less frequently (OR 0.12, p < 0.0001), and had concurrent lower total and high-density lipoprotein cholesterol concentrations that resulted in unaltered atherogenic indices (p = 0.2) than the other participants in the study. These findings translated into global scores for major conventional risk factor-mediated future CVD event rates that were not reduced in black patients. Proportions of individual metabolic syndrome components differed between black and other patients but their total numbers of metabolic risk factors (p = 0.4) and metabolic syndrome frequencies (OR 1.44, p = 0.1) were similar. Black ethnicity did not independently associate with rheumatoid factor status, markers of inflammation, and brachial pulse pressures.

CONCLUSION

The overall conventional and nonconventional atherosclerotic CVD risk burdens and arterial stiffness were not reduced in black patients with RA. CVD risk should be assessed and managed independent of ethnic origin and epidemiological transition stage in RA.

The effect of patients' race on provider treatment choices in coronary care: a literature review for model development

This selective literature review provides insight into the depth and breadth of the problem of unequal medical treatment of Blacks compared with Whites, with particular focus on coronary heart disease. Poor health outcomes among Blacks, when compared with Whites, are well documented, and these disparities are linked to lower quality of and less aggressive medical treatment. It is not clear why these disparities in treatment occur. This review provides theoretical frameworks that attempt to explain the effect of race on treatment and presents an analysis of the quality and strength of existing evidence of racial disparity related to coronary care. Based on the review, implications for policy makers and providers are identified.

Racial differences in endotoxin-induced tissue factor-triggered coagulation

BACKGROUND

Racial differences in coagulation are poorly understood. While some studies suggest a 'prothrombotic' coagulation profile in blacks compared with whites, others report an increased bleeding risk for blacks in various clinical settings. Moreover, preclinical data suggest a link between the Duffy antigen (=DARC, Duffy antigen receptor of chemokines) and coagulation.

OBJECTIVES

Based on our previous research in Duffy antigen negative Africans, we hypothesized that Africans have an attenuated procoagulant response compared with Caucasians in a model of lipopolysaccharide (LPS)-induced, tissue factor (TF)-triggered coagulation activation.

PATIENTS/METHODS

Healthy male volunteers (16 Duffy-negative Africans, 16 Duffy-positive Caucasians) received 2 ng kg(-1) LPS, and outcome parameters were measured using enzyme immunoassays and real-time polymerase chain reaction (RT-PCR, Taqman).

RESULTS

LPS increased microparticle (MP)-associated TF procoagulant activity (PCA) less in Africans than Caucasians. Africans had reduced in vivo thrombin formation compared with Caucasians: they generated less thrombin-antithrombin (TAT) complexes (10.4 pg mL(-1) vs. 23.0 pg mL(-1), P<0.0001) and less prothrombin fragments (F1+2) (337 pmol mL(-1) vs. 819 pmol mL(-1), P<0.0001). Consistently, Africans also had decreased fibrin formation (D-dimer: 0.3 pg mL(-1) vs. 0.5 pg mL(-1), P=0.02).

CONCLUSION

Duffy-negative subjects of African descent have a markedly reduced procoagulant response in a model of LPS-induced, TF-triggered coagulation activation compared with Duffy-positive healthy Caucasians.

Age-related changes in dorsal root ganglia, circulating and vascular calcitonin gene-related peptide (CGRP) concentrations in female rats: effect of female sex steroid hormones

The aim of the present study is to investigate whether immunoreactive (I) calcitonin gene-related peptide (CGRP) content is decreased in plasma and mesenteric arteries (resistance arteries) in middle-aged rats and if so, whether sex steroid hormones enhance I-CGRP in middle-aged female rats. We also examined whether vascular CGRP receptor components, calcitonin receptor like receptor (CRLR) and receptor activity modifying protein 1 (RAMP1) are elevated by sex steroid hormones treatment in middle-aged female rats. Young adult (3 months old) and middle-aged (10-12 months old) ovariectomized rats were treated subcutaneously with estradiol-17beta (E2; 2 mg), progesterone (P4; 5 mg), E2+P4 (2 mg+20 mg) or placebo (control). Radioimmunoassay and Western blot analysis were performed to measure I-CGRP content and CGRP receptor components in dorsal root ganglia (DRG), in resistance arteries and in plasma. Immunofluorescent staining methods were employed to determine cellular localization of CRLR, RAMP1 in resistance arteries. Our data demonstrated that I-CGRP content was significantly (p<0.05) lower in the plasma and resistance arteries of middle-aged female rats compared to young controls. Both RAMP1 and CRLR were concentrated in vascular endothelium and the underlying smooth muscle cells. RAMP1 but not CRLR appeared to be decreased in middle-aged rat vasculature. Chronic perfusion of sex steroid hormones to ovariectomized rats: 1 significantly (p<0.05) elevated I-CGRP in the DRG and in the plasma, and (2) significantly elevated RAMP1 (p<0.05) but did not alter CRLR in resistance arteries. These data suggest that female sex steroid treatment enhances I-CGRP and its receptors, and thus regulate the blood pressure in aged female rats.

Relationship between heart rate variability, interleukin-6, and soluble tissue factor in healthy subjects

Decreased heart rate variability (HRV) has been associated with an increased risk of atherosclerosis. We hypothesized that a decrease in frequency domains of resting HRV would be associated with elevated plasma levels of interleukin (IL)-6 and soluble tissue factor (sTF) both previously shown to prospectively predict atherothrombotic events in healthy subjects. Subjects were 102 healthy and unmedicated black and white middle-aged men and women. We determined IL-6 and sTF antigen in plasma and HRV measures from surface electrocardiogram data using spectral analysis. All statistical analyses controlled for age, gender, ethnicity, smoking status, blood pressure, and body mass index. Low amounts of low frequency (LF) power (beta=-0.31, p=0.007) and high frequency (HF) power (beta=-0.36, p=0.002) were associated with increased amounts of IL-6, explaining 7% and 9% of the variance, respectively. Interactions between LF power and IL-6 (p=0.002) and between HF power and IL-6 (p=0.012) explained 8% and 5%, respectively, of the variance in sTF. Post hoc analyses showed associations between IL-6 and sTF when LF power (beta=0.51, p<0.001) and HF power (beta=0.48, p<0.001) were low but not when LF power and high HF power were high. The findings suggest that systemic low-grade inflammatory activity is associated with a decrease in HRV. Furthermore, there was a positive relationship between plasma levels of IL-6 and sTF antigen when HRV was low. Inflammation and related hypercoagulability might particularly contribute to atherothrombotic events in a setting of decreased HRV.

The "Hispanic paradox": an investigation of racial disparity in pregnancy outcomes at a tertiary care medical center

OBJECTIVE

The purpose of this study was to examine racial disparities and the "Hispanic paradox" in pregnancy outcomes at a tertiary-care medical center.

STUDY DESIGN

A cross-sectional study of pregnancy events was performed with information from the Duke University birth database. The latter includes data on birth outcomes, cost, and health services factors. The final sample included 10,755 women with Medicaid insurance, who gave birth during calendar years 1994-2004. Pregnancy comorbidities and outcome measures were identified by International Classification of Diseases, 9th revision, and Current Procedural Terminology (CPT) codes. Univariate and multivariate analyses were performed to compare racial/ethnic groups.

RESULTS

African-American women were younger and more likely to be employed, to have a medical comorbidity, to remain in the hospital for >4 days, and to have hospital charges of >$7500. African-American women had higher rates of preterm birth, small-for-gestational-age infants, preeclampsia, and stillbirths. There were no differences by race for gestational diabetes mellitus. With the use of white women as the reference group, Hispanic women had lower odds for preterm birth (odds ratio, 0.66; 95% CI, 0.54-0.80), and African-American women had greater odds for preeclampsia (odds ratio, 1.30; 95% CI, 1.07-1.58) and small-for-gestational-age infants (odds ratio, 1.74; 95% CI, 1.29-2.36). With the use of African-American women as the reference, Hispanic women were less likely than African-American women to experience any adverse pregnancy event, with the exception of gestational diabetes mellitus.

CONCLUSION

Poverty and insurance status does not explain differences in adverse pregnancy outcomes between African-American women and Hispanic women with Medicaid insurance.

Association of novel risk factors with the ankle brachial index in African American and non-Hispanic white populations

OBJECTIVES

To investigate whether novel risk factors, including C-reactive protein (CRP), fibrinogen, lipoprotein(a) [Lp(a)], and homocysteine levels, are associated with the ankle brachial index (ABI) in African American and non-Hispanic white populations and whether novel risk factors account for ethnic differences in peripheral arterial disease (PAD).

PARTICIPANTS AND METHODS

Between December 2000 and October 2004, original participants in the Genetic Epidemiology Network of Arteriopathy study returned for a second study visit to undergo measurement of risk factors and ABI. The CRP, Lp(a), and homocysteine levels were log transformed to reduce skewness. Multivariable regression analyses were used to assess whether a novel risk factor was associated with ABI after adjustment for conventional risk factors and whether ethnicity was associated with PAD (ABI, <or=0.95) after adjustment for conventional and novel risk factors.

RESULTS

Of 2229 study participants, the ABI was determined in 1395 African American participants (mean +/- SD age, 63 +/- 9 years; 71% women) and 834 white participants (mean +/- SD age, 58 +/- 9 years; 62% women) who belonged to hypertensive sibships. The mean ABI was lower in African American than in white individuals (0.99 +/- 0.1 vs 1.13 +/- 0.1; P < .001). In both ethnic groups, higher levels of CRP, fibrinogen, and homocysteine were each associated with a lower ABI after adjustment for conventional risk factors. In African American participants, the Lp(a) level was also significantly associated with the ABI. African American ethnicity was associated with the presence of PAD after adjustment for conventional risk factors (men: odds ratio [OR], 3.04; 95% confidence interval [CI], 1.80-5.15; women: OR, 2.82; 95% CI, 1.85-4.29), but the risk was significantly attenuated after additional adjustment for novel risk factors (men: OR, 2.11; 95% CI, 1.21-3.70; women: OR, 1.98; 95% CI, 1.26-3.11).

CONCLUSION

Novel risk factors are associated with interindividual variation in ABI in African American and non-Hispanic white populations and partly account for the increased risk of PAD associated with African American ethnicity.

Health state information derived from secondary databases is affected by multiple sources of bias

OBJECTIVE

Secondary databases are used in descriptive studies of patient subgroups; evaluation of associations between individual characteristics and diagnosis, prognosis, and/or service utilization rates; and studies of the quality of health care delivered. This article identifies sources of bias for health state characteristics stored in secondary databases that arise from patients' encounters with health systems, highlighting sources of bias that arise from organizational and environmental factors.

STUDY DESIGN AND SETTING

Potential sources of bias, from patient access of services and diagnosis, through encoding and filing of patient information in secondary databases, are discussed. A patient presenting with acute myocardial infarction is used as an illustrative example.

RESULTS

The accuracy of health state characteristics derived from secondary databases is a function of both the quality and quantity of information collected before data entry and is dependent on complex interactions between patients, clinicians, and the structures and systems surrounding them.

CONCLUSION

The use of health state information included in secondary databases requires that estimates of potential bias from all sources be included in the analysis and presentation of results. By making this common practice in the field, greater value can be achieved from secondary database analyses.