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Heart Disease & Blacks
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"The high risk of presenting with death as the first manifestation of CHD among black men and women, which is associated with excess burden of cardiovascular disease risk factors, is similar to past reports4 - 7 and demonstrates little evidence of progress toward eliminating this disparity." JAMA Nov 7 2012
Two NIH landmark studies show power of epidemiology research; underscore need to address health disparities
· Hispanic Community Health Study/Study of Latinos (HCHS-SOL)-which will be presented at the American Heart Association Annual Meeting in Los Angeles on Nov. 5 and published in the Nov. 7 issue of the Journal of the American Medical Association (JAMA)-finds heart disease risk factors are widespread among Hispanic/Latino adults in the United States.
· Reasons for Geographic and Racial Differences in Stroke (REGARDS) study-which will be published in the Nov. 7 issue of JAMA-finds black men and women are about twice as likely to die from coronary heart disease (CHD) compared with their age-matched white counterparts.
Rates of heart disease risk factors vary across Hispanic/Latino populations
Heart disease risk factors are widespread among Hispanic/Latino adults in the United States, with 80 percent of men and 71 percent of women having at least one risk factor for heart disease, according to a study funded by the National Institutes of Health. The Hispanic Community Health Study/Study of Latinos (HCHS-SOL) is the largest study to date to examine the prevalence of heart disease risk factors-high blood pressure, high cholesterol, obesity, diabetes, and smoking-within a diverse Hispanic/Latino population.
Findings from HCHS-SOL also showed that the prevalence of risk factors varies across and within Hispanic/Latino populations. For example, people of Puerto Rican background experienced higher rates of heart disease risk factors compared to other Hispanic/Latino groups.
Participants who were more acculturated (born in the United States or lived in the United States for 10 years or longer or preferred using English rather than Spanish) were significantly more likely to have three or more risk factors as well as self-reported heart disease or stroke. And those with lower education or with annual incomes less than $20,000 were more likely to have multiple heart disease risk factors than those with higher education and incomes.
"Heart disease is the leading cause of death among Hispanic/Latino people in the United States, so it was critical to conduct a study that looked at the burden of heart disease risk factors in specific populations," said Larissa Aviles-Santa, M.D., M.P.H., project officer for HCHS/SOL in the National Heart, Lung, and Blood Institute (NHLBI) Division of Cardiovascular Sciences, part of the NIH.
HCHS-SOL is a multi-center, prospective, population-based study that includes more than 16,000 Hispanic/Latino adults of different backgrounds-including Cuban, Dominican, Mexican, Puerto Rican, Central American, and South American-between the ages of 18 and 74.
The participants were recruited from randomly selected households in four U.S. communities: the New York City borough of the Bronx, Chicago, Miami, and San Diego. Participants underwent an extensive baseline examination and also completed questionnaires about their medical history, lifestyle, education, annual income, and acculturation. Data were collected from participants between March 2008 and June 2011 and then analyzed.
"The results of the HCHS-SOL study show the need to implement education and lifestyle change programs to lessen the burden of heart disease risk factors among Hispanic/Latino people, starting at early ages," said Martha Daviglus, M.D., Ph.D., principal investigator for the HCHS-SOL Chicago site, professor of preventive medicine at Northwestern University, and director of the Institute for Minority Health Research at the University of Illinois at Chicago.
"A better understanding of the relationship between traditional lifestyles, acculturation, and development of cardiovascular disease over time will provide us with the information needed to create programs that will reduce the burden of cardiovascular risk factors among Hispanics/Latinos," said Greg Talavera, M.D., M.P.H, principal investigator for the HCHS-SOL San Diego site and professor at the San Diego State University.
Findings from this phase of the study include self-reported history of heart disease and stroke, and clinically measured risk factors. The study team will continue to follow the participants to learn how risk factors change over time and how they influence the risk of developing cardiovascular disease.
HCHS-SOL activities were conducted by more than 250 staff members at four field centers affiliated with San Diego State University, Northwestern University and the University of Illinois at Chicago, Albert Einstein College of Medicine in New York City, and the University of Miami. The Collaborative Studies Coordinating Center at the University of North Carolina in Chapel Hill provided additional support.
HCHS-SOL is supported by the NHLBI and six other NIH institutes and offices, including the National Institute of Diabetes and Digestive and Kidney Diseases, National Institute on Minority Health and Health Disparities, National Institute on Deafness and Other Communication Disorders, National Institutes of Dental and Craniofacial Research, National Institute of Neurological Disorders and Stroke, and the Office of Dietary Supplements.
HCHS-SOL is supported by contracts from the NHLBI to the University of North Carolina (N01-HC65233), University of Miami (N01-HC65234), Albert Einstein College of Medicine (N01-HC65235), Northwestern University (N01-HC65236), and San Diego State University (N01-HC65237).
NIH study points to higher mortality in African Americans
Researchers from the NIH-supported Reasons for Geographic and Racial Differences in Stroke (REGARDS) study found that black men and women were about twice as likely to die from coronary heart disease (CHD) compared with their age-matched white counterparts. Black women had a higher incidence of fatal and nonfatal coronary disease than white women. The findings are based on an analysis of 24,443 men and women.
For the past nine years, the REGARDS study team has been tracking stroke risk and cognitive health in an ethnically and demographically diverse sample of more than 30,000 adults in the United States.
"This research shows clearly that there is much work to be done in addressing racial health disparities. We haven't been able to move the needle in this important population that is disproportionately affected by coronary heart disease and stroke," said Walter J. Koroshetz, M.D., deputy director of the National Institute of Neurological Disorders and Stroke (NINDS). "It highlights the need for a campaign to control known vascular risk factors that lead to premature death and loss of quality of life."
The current analysis, spearheaded by researchers at the University of Alabama at Birmingham, also showed that the disparity in CHD deaths between blacks and whites is due largely to an excess burden of known cardiovascular risk factors among blacks. None of the participants had evidence of CHD at baseline and they were followed for four years. As shown in previous studies, death was far more likely to be the first indication of CHD in blacks than it was in whites, suggesting that there has been "little evidence of progress toward eliminating this disparity," according to the paper. "Well-established CHD risk factors among blacks could potentially reduce these disparities," the researchers concluded.
REGARDS is supported by the NINDS. This specific research project was supported by grants from the NIH's NHLBI (R01 HL080477) and the National Center for Research Resources (KL2 RR025776-04), as well as a cooperative agreement from NINDS (U01 NS041588). Additional support was provided by an investigator-initiated grant-in-aid from Amgen Corporation.
"These two reports send a powerful and sobering message," noted Michael Lauer, M.D., director of the Division of Cardiovascular Sciences at the NHLBI, in an accompanying JAMA editorial. "Despite 50 years of epidemiological knowledge and numerous therapeutic advances, risk factor burdens among minority populations are unacceptably high and consequential."
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November 7, 2012
Association of Race and Sex With Risk of Incident Acute Coronary Heart Disease Events
Monika M. Safford, MD; Todd M. Brown, MD, MSPH; Paul M. Muntner, PhD; Raegan W. Durant, MD, MPH; Stephen Glasser, MD; Jewell H. Halanych, MD, MSc; James M. Shikany, DrPH; Ronald J. Prineas, MD, PhD; Tandaw Samdarshi, MD; Vera A. Bittner, MD, MSPH; Cora E. Lewis, MD, MSPH; Christopher Gamboa, MPH; Mary Cushman, MD; Virginia Howard, PhD; George Howard, DrPH; for the REGARDS Investigators
JAMA
ABSTRACT
Context It is unknown whether long-standing disparities in incidence of coronary heart disease (CHD) among US blacks and whites persist.
Objective To examine incident CHD by black and white race and by sex.
Design, Setting, and Participants Prospective cohort study of 24 443 participants without CHD at baseline from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, who resided in the continental United States and were enrolled between 2003 and 2007 with follow-up through December 31, 2009.
Main Outcome Measure Expert-adjudicated total (fatal and nonfatal) CHD, fatal CHD, and nonfatal CHD (definite or probable myocardial infarction [MI]; very small non-ST-elevation MI [NSTEMI] had peak troponin level <0.5 μg/L).
Results Over a mean (SD) of 4.2 (1.5) years of follow-up, 659 incident CHD events occurred (153 in black men, 138 in black women, 254 in white men, and 114 in white women). Among men, the age-standardized incidence rate per 1000 person-years for total CHD was 9.0 (95% CI, 7.5-10.8) for blacks vs 8.1 (95% CI, 6.9-9.4) for whites; fatal CHD: 4.0 (95% CI, 2.9-5.3) vs 1.9 (95% CI, 1.4-2.6), respectively; and nonfatal CHD: 4.9 (95% CI, 3.8-6.2) vs 6.2 (95% CI, 5.2-7.4). Among women, the age-standardized incidence rate per 1000 person-years for total CHD was 5.0 (95% CI, 4.2-6.1) for blacks vs 3.4 (95% CI, 2.8-4.2) for whites; fatal CHD: 2.0 (95% CI, 1.5-2.7) vs 1.0 (95% CI, 0.7-1.5), respectively; and nonfatal CHD: 2.8 (95% CI, 2.2-3.7) vs 2.2 (95% CI, 1.7-2.9). Age- and region-adjusted hazard ratios for fatal CHD among blacks vs whites was near 2.0 for both men and women and became statistically nonsignificant after multivariable adjustment. The multivariable-adjusted hazard ratio for incident nonfatal CHD for blacks vs whites was 0.68 (95% CI, 0.51-0.91) for men and 0.81 (95% CI, 0.58-1.15) for women. Of the 444 nonfatal CHD events, 139 participants (31.3%) had very small NSTEMIs.
Conclusions The higher risk of fatal CHD among blacks compared with whites was associated with cardiovascular disease risk factor burden. These relationships may differ by sex.
Although mortality rates for acute myocardial infarction (MI) and coronary heart disease (CHD) have declined in the United States since the 1970s,1 - 4 both death certificate data and evidence from 4 US communities suggest a steeper decline in acute CHD mortality between 2000 and 2008 for whites than for blacks, widening a long-standing disparity.5 - 6 Furthermore, data from Kaiser Permanente suggested that hospitalizations for MI decreased between 2002 and 2007,7 but more so for whites than for blacks. Neither death certificate data nor health plan data permit examination of incident events.5 ,8 - 10
Two other major secular trends may influence contemporary estimates of incident CHD. First, statins have come into wide use over the past 10 years,11 lowering incidence rates. Second, cardiac troponin assays have become increasingly sensitive and very small amounts of myocardial necrosis are now routinely detected. Even very small non-ST-elevation MIs (NSTEMIs), with peak troponin level of less than 0.5 μg/L, may confer similar long-term risks as larger MIs.12 - 14 However, very small NSTEMIs have only recently been included in studies of MI event rates, resulting in higher reported MI incidence rates. The overall effect of these secular trends on estimates of CHD incidence and racial disparities is unclear.
We analyzed data from the national Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort with 3 objectives: (1) to examine racial and sex differences in incident total CHD, fatal CHD, and nonfatal CHD across race-sex groups, (2) to examine whether risk factors were associated with observed race-sex risk differences, and (3) to examine race-sex differences in participants with very small NSTEMIs.
COMMENT
In the REGARDS study, black men and black women had twice the age-standardized rate of fatal incident CHD compared with white men and white women. This increased risk was associated with racial differences in CHD risk factors, which were more prevalent among black men and women compared with white men and women. A marked sex difference was present for nonfatal acute CHD: black men had a lower risk of presenting with incident nonfatal acute MI than white men, but black women had a higher risk than white women. The low risk in black men remained present in the fully adjusted models, but the excess risk observed among black women was entirely attenuated after accounting for their higher cardiovascular disease risk factor burden. The high risk of presenting with death as the first manifestation of CHD among black men and women, which is associated with excess burden of cardiovascular disease risk factors, is similar to past reports4 - 7 and demonstrates little evidence of progress toward eliminating this disparity.
The incidence rates we observed were consistent with other reports of continued downward trends in MI and acute CHD mortality. There are relatively few biracial cohorts that provide incidence data in the United States. Incidence rates for CHD from the Atherosclerosis Risk in Communities (ARIC) study were substantially higher per 1000 person-years in the 1990s than in our study (10.6 for black men, 12.5 for white men, 5.1 for black women, and 4.0 for white women).34 Of note, coronary revascularizations were included as CHD events in that report. The use of these procedures has increased dramatically since that time, albeit with some recent decreases,22 and we observed lower revascularization use among black vs white REGARDS participants. More recently, the ARIC surveillance study reported declines in CHD death without history of MI as well as first MI from 1987 through 2008, revealing larger declines for whites than for blacks, with the lowest decline found in black men and an increase in first MI among black men.5 These results support the continued disparities in CHD we observed.
The racial and sex differences in fatal vs nonfatal acute CHD incidence rates that we observed are, to our knowledge, new. In the ARIC study, the incidence of overall CHD was similar for black and white men and for black and white women, but nonfatal and fatal events were not reported separately.34 A recent analysis of pooled ARIC and Cardiovascular Health Study data compared risks of sudden cardiac death (SCD) and non-SCD CHD (nonfatal CHD, including revascularization procedures, and fatal CHD judged not to be SCD) over 14 years ending in 2002.35 This study reported a HR of 1.81 (95% CI, 1.31-2.49) for SCD for blacks compared with whites and a HR of 0.76 (95% CI, 0.67-0.86) for non-SCD. While these categories are not directly comparable with ours, the results are generally concordant. Our more recent results, taken together with prior studies, suggest there has been disappointingly little progress in lowering the excess risk of death at first clinical presentation of acute CHD among blacks.
To our knowledge, previous reports have not found the lower risk of incident nonfatal CHD among black men that we described. The additional analyses we conducted did not support that all-cause mortality was a competing risk, or that procedure-related MI, which potentially could have inflated nonfatal CHD in white men, contributed substantially. The low risk was seen only for typical MIs but not very small NSTEMIs. Additional studies are needed to confirm these findings.
The role of very small NSTEMI in the incidence of acute CHD is an emerging phenomenon. Numerous reports confirm the long-term risks associated with very small NSTEMIs, and experts including the European Society of Cardiology, the American College of Cardiology Federation, the American Heart Association, and the World Heart Federation recommend classifying such events as MIs.14 ,18 ,36 - 40 The large proportion of very small NSTEMIs suggests that comparisons of contemporary with past incidence rates will be complicated, especially for studies of racial disparities if our findings across race and sex groups are confirmed in other studies. In addition, the optimal threshold for defining very small NSTEMI is not clear; past reports that included estimates of the incidence of very small NSTEMI relative to typical MIs used varying definitions of this entity.14 ,38 - 39 ,41 We selected a conservative threshold but other thresholds may be reasonable, and consensus on how to define very small NSTEMI across epidemiological studies may be warranted, along with consensus on how to handle very small NSTEMI for comparisons with past studies.
Limitations of this study include its observational design and attendant cautions about drawing causal inferences. The REGARDS cohort was not designed as a surveillance study; thus, we likely underestimated incidence for nonfatal CHD events but not for fatal CHD events, which have more complete ascertainment. Although the REGARDS cohort has wide reach, participants in any research study may differ from the general population, affecting generalizability. Some of our covariates were self-reported, which carries limitations. Future analyses will permit more in-depth exploration of very small NSTEMIs.
Strengths of this study include its national scope and unique in-home data collection, facilitating participation from residents of geographic areas beyond driving distance of large research institutions. The large number of geographically dispersed black and white participants is another notable strength, as is the contemporaneous nature of the cohort, with ongoing follow-up and rigorous adjudication of events using published guidelines, including conducting interviews with next of kin.
CONCLUSIONS
Similar incidence rates of total CHD among men obscured marked racial differences in fatal and nonfatal CHD. Fatal CHD risk was higher among black men and associated with known risk factors, but nonfatal CHD risk was lower with and without risk factor adjustment. In contrast, black women had higher rates of total, fatal, and nonfatal CHD, with higher risks attenuated by known risk factors. Excess risk factor burden among black men and women continues to be a major public health challenge, along with their high risk for death as the presentation of CHD. Increased emphasis on optimizing well-established CHD risk factors among blacks could potentially reduce these disparities.
RESULTS
Sample Characteristics
After excluding 5314 individuals with baseline CHD and 426 without follow-up, the study sample included 24 443 participants (Table 1). Blacks and whites had a similar mean age, but blacks had less education and a lower income level. Smoking, diabetes, and reduced estimated GFR were more prevalent and systolic blood pressure, BMI, and level of high-sensitivity CRP were higher among blacks than whites.
Incidence Rates
The mean (SD) follow-up time was 4.2 (1.5) years. The 659 total incident CHD events through December 31, 2009, included 153 events in black men, 254 in white men, 138 in black women, and 114 in white women (Table 2). Although the incidence rate per 1000 person-years of total CHD was similar among black men (9.0; 95% CI, 7.5-10.8) and white men (8.1; 95% CI, 6.9-9.4), black men had higher incidence of fatal CHD (4.0 [95% CI, 2.9-5.3] vs 1.9 [95% CI, 1.4-2.6] for white men) and lower incidence of nonfatal CHD (4.9 [95% CI, 3.8-6.2] vs 6.2 [95% CI, 5.2-7.4] for white men; Figure). Women had lower incidence rates per 1000 person-years than men within each racial group. However, black women had higher incidence rates per 1000 person-years for total CHD (5.0 [95% CI, 4.2-6.1] vs 3.4 [95% CI, 2.8-4.2] for white women), for fatal CHD (2.0 [95% CI, 1.5-2.7] vs 1.0 [95% CI, 0.7-1.5] for white women), and for nonfatal CHD (2.8 [95% CI, 2.2-3.7] vs 2.2 [95% CI, 1.7-2.9] for white women; Figure).
Risks for CHD
For total CHD, the age- and region-adjusted HR for black men compared with white men was 1.15 (95% CI, 0.94-1.41) (model 1) and in the fully adjusted model it was 0.87 (95% CI, 0.69-1.08; model 4) (Table 3). Among women, the age- and region-adjusted HR for total CHD for blacks vs whites was 1.48 (95% CI, 1.15-1.90) and in the fully adjusted model it was 0.90 (95% CI, 0.68-1.20).
For fatal CHD, the age- and region-adjusted HR for black men compared with white men was 2.18 (95% CI, 1.55-3.06) and in the fully adjusted model it was 1.34 (95% CI, 0.91-1.96). Among women, the age- and region-adjusted HR for fatal CHD for blacks vs whites was 1.93 (95% CI, 1.23-3.03) and in the fully adjusted model it was 1.14 (95% CI, 0.69-1.99) (Table 3).
For nonfatal CHD, the age- and region-adjusted HR for black men compared with white men was 0.81 (95% CI, 0.63-1.06) and in the fully adjusted model it was 0.68 (95% CI, 0.51-0.91). Among women, the age- and region-adjusted HR for nonfatal CHD for blacks vs whites was 1.31 (95% CI, 0.97-1.77) and in the fully adjusted model it was 0.81 (95% CI, 0.58-1.15) (Table 3).
Role of Very Small NSTEMI
Very small NSTEMI comprised 31.3% of nonfatal CHD events; there were 33 (40.2%) among black men, 47 (24.6%) among white men, 35 (39.8%) among black women, and 24 (28.9%) among white women (Table 2). Incidence rates for typical MI were lower for black men than for white men, but rates for very small NSTEMI were similar (eFigure 1). In contrast, incidence rates for typical MI were similar for black women and white women, but incidence rates for very small NSTEMI were higher for black women than for white women.
The HRs for typical MI for blacks vs whites were similar to the overall nonfatal CHD results for both men and women (Table 4). The HR for very small NSTEMI was not statistically different for black men vs white men, but black women had a higher age-adjusted HR for very small NSTEMI vs white women, which became nonsignificant with full adjustment.
Sensitivity Analyses
Including coronary revascularization procedures substantially and disproportionately increased the age-standardized incidence rates for whites vs blacks. For white men, total CHD increased by 69.3% and nonfatal CHD increased by 93.7%; for white women, total CHD increased by 63.2% and nonfatal CHD increased by 86.7%. For black men, total CHD increased by 21.6% and nonfatal CHD increased by 42.7%; for black women, total CHD increased by 34.1% and nonfatal CHD increased by 54.5%. Effects on fatal CHD were trivial (eTable 1 and eFigure 2). For men, the HRs for blacks compared with whites for incident total and nonfatal CHD were lower than in the model without revascularizations, but there were minimal changes in the HRs for incident fatal CHD comparing black men with white men (eTable 2). For black women compared with white women, higher HRs for total CHD became significantly lower in the fully adjusted models; multivariable-adjusted HRs for nonfatal CHD also were significantly lower. Higher HRs for fatal CHD became nonsignificant with multivariable adjustment (eTable 2).
Accounting for the competing risk of all-cause mortality among blacks had little effect on the risks for nonfatal CHD (adjusted HRs comparing blacks with whites: 0.59 [95% CI, 0.46-0.78] for men and 0.87 [95% CI, 0.64-1.18] for women without revascularizations; adjusted HRs comparing blacks with whites: 0.44 [95% CI, 0.36-0.55] for men and 0.72 [95% CI, 0.56-0.91] for women with revascularizations). There were 10 procedure-related MIs among black men and 23 among white men; the results including procedure-related MIs were almost identical to those that did not include these events.
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