Pathogenesis of Hypertension in African Americans

Racial Differences in Diuretic Efficiency, Plasma Renin, and Rehospitalization in Subjects With Acute Heart Failure

BACKGROUND

Black patients have higher rates of hospitalization for acute heart failure than other race/ethnic groups. We sought to determine whether diuretic efficiency is associated with racial differences in risk for rehospitalization after acute heart failure.

METHODS

A post hoc analysis was performed on 721 subjects (age, 68±13 years; 22% black) enrolled in 3 acute heart failure clinical trials: ROSE-AHF (Renal Optimization Strategies Evaluation in Acute Heart Failure), DOSE-AHF (Diuretic Optimization Strategy Evaluation in Acute Decompensated Heart Failure), and CARRESS-HF (Cardiorenal Rescue Study in Acute Decompensated Heart Failure). Repeated-measures ANOVA was used to test for a race×time effect on measures of decongestion. Diuretic efficiency was calculated as net fluid balance per total furosemide equivalents. In a subset of subjects, Cox regression was used to examine the association between race and rehospitalization according to plasma renin activity (PRA).

RESULTS

Compared with nonblack patients, black patients were younger and more likely to have nonischemic heart failure. During the first 72 to 96 hours, there was greater fluid loss (P=0.001), decrease in NT-proBNP (N-terminal pro-B-type natriuretic peptide; P=0.002), and lower levels of PRA (P<0.0001) in black patients. Diuretic efficiency was higher in black than in nonblack patients (403 [interquartile range, 221-795] versus 325 [interquartile range, 154-698]; P=0.014). However, adjustment for baseline PRA attenuated the association between black race and diuretic efficiency. Over a median follow-up of 68 (interquartile range, 56-177) days, there was an increased risk of all-cause and heart failure-specific rehospitalization in nonblack patients with increasing levels of PRA, while the risk of rehospitalization was relatively constant across levels of PRA in black patients.

CONCLUSIONS

Higher diuretic efficiency in black patients with acute heart failure may be related to racial differences in activity of the renin-angiotensin-aldosterone system.

Beyond JNC 8: implications for evaluation and management of hypertension in underserved populations

In the United States, hypertension is a significant medical problem that affects nearly 1 in 3 adults, causes thousands of deaths annually, and costs the nation billions of dollars annually for medical management in terms of hospitalisations, lost wages, and pharmacotherapy. The management guidelines of hypertension have greatly varied between different healthcare organisations including the American College of Cardiology (ACC), the European Society of Cardiology (ESC) and the Joint National Committee (JNC-7, 8). One of the points of contention is the generalisability of the guidelines to all individuals despite empirical evidence suggesting racial sensitivities to pharmacotherapy and high clinical adversities with elevations in blood pressure (BP). This manuscript will aim to review a brief history of the guidelines, the adjustment of the BP goals with pharmacotherapy for the management of hypertension, and discuss several socioeconomic factors attributing to higher clinical risks for certain minority racial groups susceptible to the new BPs goals for management under the JNC-8.

Disentangling Race and Socioeconomic Status in HealthDisparities Research: an Examination of Black and White Clergy

AIM

Sophisticated adjustments for socioeconomic status (SES) in health disparities research may help illuminate the independent role of race in health differences between Blacks and Whites. In this study of people who share the same occupation (United Methodist Church clergy) and state of residence (North Carolina), we employed naturalistic and statistical matching to estimate the association between race-above and beyond present SES and other potential confounds-and health disparities.

METHODS

We compared the health of 1414 White and 93 Black clergy. Then, we used propensity scores to match Black and White participants on key socioeconomic, demographic, occupational, and physical activity characteristics and re-examined differences in health.

RESULTS

Prior to propensity score matching, Black clergy reported worse physical health than their White counterparts. They had greater body mass index, higher prevalence of diabetes and hypertension, and lower physical health functioning. White clergy reported less favorable mental health. They had higher severity of depression and anxiety symptoms as well as lower quality of life and mental health functioning. Propensity score analysis revealed that matching on SES and other key variables accounted for most, but not all, of the observed racial differences. Racial disparities in hypertension, depression severity, and mental health functioning persisted despite adjustments.

CONCLUSIONS

Race contributed to health disparities in some outcomes in our study population, above and beyond our measures of participants' present SES and key demographic, occupational, and physical activity variables. This study provides evidence supporting the position that race contributes to health disparities through pathways other than SES.

Hypertension in African Americans

PURPOSE OF REVIEW

African Americans are over-burdened with hypertension resulting in excess morbidity and mortality. We highlight the health impact of hypertension in this population, review important observations regarding disease pathogenesis, and outline evidence-based treatment, current treatment guidelines, and management approaches.

RECENT FINDINGS

Hypertension accounts for 50% of the racial differences in mortality between Blacks and Whites in the USA. Genome-wide association studies have not clearly identified distinct genetic causes for the excess burden in this population as yet. Pathophysiology is complex likely involving interaction of genetic, biological, and social factors prevalent among African Americans. Non-pharmacologic and pharmacologic therapy is required and specific treatment guidelines for this population are varied. Combination therapy is most often necessary and single-pill formulations are most successful in achieving BP targets. Racial health disparities related to hypertension in African Americans are a serious public health concern that warrants greater attention. Multi-disciplinary research to understand the inter-relationship between biological and social factors is needed to guide successful treatments. Comprehensive care strategies are required to successfully address and eliminate the hypertension burden.

Cumulative Lactation and Onset of Hypertension in African-American Women

Hypertension affects nearly 1 of 3 women and contributes to cardiovascular disease, the leading cause of death in the United States. Breastfeeding leads to metabolic changes that could reduce risks of hypertension. Hypertension disproportionately affects black women, but rates of breastfeeding among black women lag behind those in the general population. In the Black Women's Health Study (n = 59,001), we conducted a nested case-control analysis using unconditional logistic regression to estimate the association between breastfeeding and incident hypertension at ages 40-65 years using data collected from 1995 to 2011. Controls were frequency-matched 2:1 to 12,513 hypertensive women by age and questionnaire cycle. Overall, there was little evidence of association between ever breastfeeding and incident hypertension (odds ratio = 0.97, 95% confidence interval: 0.92, 1.02). However, age modified the relationship (P = 0.02): Breastfeeding was associated with reduced risk of hypertension at ages 40-49 years (odds ratio = 0.92, 95% confidence interval: 0.85, 0.99) but not at older ages. In addition, risk of hypertension at ages 40-49 years decreased with increasing duration of breastfeeding (P for trend = 0.08). Our results suggest that long-duration breastfeeding may reduce the risk of incident hypertension in middle age. Addressing breastfeeding as a potential preventative health behavior is particularly compelling because it is required for only a discrete period of time.

Abnormal autonomic nervous system function in rural Thai men: A potential contributor to their high risk of sudden unexplained nocturnal death syndrome

BACKGROUND

Rural compared to urban Thai populations have a higher incidence of sudden unexplained nocturnal death syndrome (SUNDS). This study tests the hypothesis that compared to young urban Thai men, the young rural northeast Thai men display autonomic system dysfunction that may contribute to their relatively high risk to develop SUNDS.

METHODS

Forty-seven healthy second and third year students from Khon Kaen University (20-22years old) were divided into central, urban northeastern, and rural northeastern groups, based on the locality in which they had grown up and in which their parents had lived prior to their birth.

RESULTS

Body weight, body height, serum sodium, serum potassium, fasting blood sugar, glucose tolerance, resting mean arterial pressure, resting heart rate, ulnar nerve conduction velocity, and sympathetic and parasympathetic nervous system activity were not significantly different among the three groups. In contrast, compared to urban northeasterners and central Thais, rural northeasterners displayed low sympathetic and high parasympathetic responses to cold stress and oral saline load; however, baroreflex sensitivity and the autonomic nervous system responses to upright tilt were not significantly different among the three groups. In addition, respiratory rates at rest and in response to upright tilt, cold stress, and oral saline load were not significantly different among the three groups.

CONCLUSIONS

These data indicate that compared to central or urban, individuals from rural origin display decreased sympathetic and increased parasympathetic responses to stresses. These altered responses could predispose the individuals to inappropriate autonomic control during the stresses, including those resulting in SUNDS.

Angiotensin II status and sympathetic activation among hypertensive patients in Uganda: a cross-sectional study

Background

Sympathetic activation and renin-angiotensin system are essential for development and sustenance of hypertension. However, the status of these systems has not been well evaluated among patients in an African setting. This study therefore set out to assess the angiotensin II status and sympathetic activation among hypertensive patients in Uganda.

Methods

In this cross sectional study conducted at Mulago, the national referral hospital, blood samples were taken to measure angiotensin II, metanephrines and normetanephrines. Urine samples were also taken for measuring urine creatinine and sodium. The angiotensin II categories were defined using the Mosby’s Diagnostic and Laboratory Test References. 9th ed while the metanephrines and normetanephrine categories were defined using the Makerere University Biosafety II Immunology Laboratory reference values.

Results

162 patients were consented and enrolled into the study, of these 136 (84 %) had low, 15 (9 %) had normal, while, 11 (7 %) had high angiotensin II levels. 142 (88 %) participants had normal levels of metanephrine, while 20 (12 %) had high levels. Only 88 were assessed for metanephrines and of these 85 (97 %) had normal, while 3 (3 %) had raised levels. Urine sodium was associated with low and normal angiotensin II levels (P value 0.007). Female gender and diastolic blood pressure were associated with a protective effect against high normetanephrines (OR 0.29, P value 0.015), 80–89 mmHg (OR 0.19, p value 0.053), above 100 mmHg (OR 0.27, p value 0.022). Current smoking status was associated with high risk for abnormal normetanephrines (OR 17.6, P value −0.022) while former smoking was associated with high risk for abnormal metanephrines (OR 18.7, p value 0.022). After multivariate analysis, all the significant variables at bivariate analysis were still significant except those who stopped smoking and those with a BP at 80–89 which were not significant.

Conclusions

Hypertensive patients in this setting have predominantly low angiotensin II hypertension as a result of high salt intake. Sympathetic activation is not a significant mechanism of hypertension in this study population, more so in the females, with the exception of smokers who have a highly activated sympathetic system. Therefore, the use of agents targeting renin angiotensin and sympathetic systems as single first line antihypertensive agents in this setting should be re-evaluated if such patients are to be treated effectively.

The Role of Hypertension in Race-Ethnic Disparities in Cardiovascular Disease

Race-ethnic disparities in cardiovascular disease (CVD) have persisted in the USA over the past few decades. Hypertension (HTN) is a significant contributor to CVD, including coronary heart disease, stroke, end-stage kidney disease and overall mortality and race-ethnic disparities in longevity. Additionally, both non-Hispanic blacks (NHBs) and Hispanic adults have been known to have higher prevalence of poorly controlled blood pressure compared to non-Hispanic whites (NHWs). Addressing these disparities has been a focus of programs such as the Million Hearts initiative. This review will provide an update of available data on HTN in various race-ethnic groups, including awareness, treatment, and control and note the recent progress in HTN control across all race/ethnic groups. We will also discuss the recent 2014 U.S. HTN guideline that has led to debate regarding the potential impact of BP goals in older persons on worsening CVD disparities, with disproportionate effects on women and NHBs.

Use of isosorbide dinitrate and hydralazine in African-Americans with heart failure 9 years after the African-American Heart Failure Trial

The 2013 American College of Cardiology Foundation/American Heart Association guidelines recommend combined isosorbide dinitrate (ISDN) and hydralazine to reduce mortality and morbidity for African-Americans with symptomatic heart failure (HF) and reduced ejection fraction, currently receiving optimal medical therapy (class I, level A). Nitrates can alleviate HF symptoms, but continuous use is limited by tolerance. Hydralazine may mitigate nitrate tolerance, and the ISDN-hydralazine combination in the Vasodilators in Heart Failure Trial (V-HeFT) I improved survival and exercise tolerance in men with dilated cardiomyopathy or HF with reduced ejection fraction, most notably in self-identified black participants. In the subsequent V-HeFT II, survival was greater with enalapril than with ISDN-hydralazine in the overall cohort, but mortality rate was similar in the enalapril and ISDN-hydralazine groups in the self-identified black patients. Consequently, in the African-American Heart Failure Trial (A-HeFT) in self-identified black patients with symptomatic HF, adding a fixed-dose combination ISDN-hydralazine to modern guideline-based care improved outcomes versus placebo, including all-cause mortality, and led to early trial termination. Hypertension underlies HF, especially in African-Americans; the A-HeFT and its substudies demonstrated not only improvements in echocardiographic parameters, morbidity, and mortality but also a decrease in hospitalizations, potentially affecting burgeoning HF health-care costs. Genetic characteristics may, therefore, determine response to ISDN-hydralazine, and the Genetic Risk Assessment in Heart Failure substudy demonstrated important hypothesis-generating pharmacogenetic data.

Hypertension in the US Black population: risk factors, complications, and potential impact of central aortic pressure on effective treatment

PURPOSE

The identification of specific factors that contribute to hypertension development and progression among blacks in the US is the focus of much ongoing research. The purpose of this paper is to review these factors and discuss how they present unique opportunities for improving the management of hypertension in this difficult-to-treat population.

METHODS

We searched the published literature for articles discussing the risk factors for hypertension and cardiovascular disease in blacks; the target-organ damage and cardiovascular complications associated with hypertension in this difficult-to-treat population; and the role of central blood pressure in predicting cardiovascular events.

RESULTS

The prevalence of hypertension is higher in blacks than in other race/ethnic groups, with environmental and genetic risk factors likely playing an important role. The cardiovascular and renal consequences of hypertension (eg, left ventricular hypertrophy and renal failure) are also greater in blacks relative to their white counterparts. Preliminary data suggest that central blood pressure may be higher in blacks than in whites and has the potential for greater prognostic capability relative to peripheral blood pressure.

CONCLUSIONS

There is an urgent need to successfully control hypertension in the black population. Although data are limited in blacks, evidence suggests that central blood pressure warrants more continued assessment in future clinical studies.

Differential Impact of Stress Reduction Programs upon Ambulatory Blood Pressure among African American Adolescents: Influences of Endothelin-1 Gene and Chronic Stress Exposure

Stress-activated gene × environment interactions may contribute to individual variability in blood pressure reductions from behavioral interventions. We investigated effects of endothelin-1 (ET-1) LYS198ASN SNP and discriminatory stress exposure upon impact of 12-week behavioral interventions upon ambulatory BP (ABP) among 162 prehypertensive African American adolescents. Following genotyping, completion of questionnaire battery, and 24-hour ABP monitoring, participants were randomized to health education control (HEC), life skills training (LST), or breathing awareness meditation (BAM). Postintervention ABP was obtained. Significant three-way interactions on ABP changes indicated that among ET-1 SNP carriers, the only group to show reductions was BAM from low chronic stress environments. Among ET-1 SNP noncarriers, under low chronic stress exposure, all approaches worked, especially BAM. Among high stress exposure noncarriers, only BAM resulted in reductions. If these preliminary findings are replicated via ancillary analyses of archival databases and then via efficacy trials, selection of behavioral prescriptions for prehypertensives will be edging closer to being guided by individual's underlying genetic and environmental factors incorporating the healthcare model of personalized preventive medicine.

Long-term impact of maternal substance use during pregnancy and extrauterine environmental adversity: stress hormone levels of preadolescent children

Prenatal cocaine exposure (PCE) is associated with blunted stress responsivity within the extrauterine environment. This study investigated the association between PCE and diurnal salivary cortisol levels in preadolescent children characterized by high biological and/or social risk (n = 725). Saliva samples were collected at their home. Analyses revealed no group differences in basal evening or morning cortisol levels; however, children with higher degrees of PCE exhibited blunted overnight increases in cortisol, controlling for additional risk factors. Race and caregiver depression were also associated with diurnal cortisol patterns. Although repeated PCE may contribute to alterations in the normal or expected stress response later in life, sociodemographic and environmental factors are likewise important in understanding hormone physiology, especially as more time elapses from the PCE. Anticipating the potential long-term medical, developmental, or behavioral effects of an altered ability to mount a normal protective cortisol stress response is essential in optimizing the outcomes of children with PCE.

Racial/ethnic residential segregation and self-reported hypertension among US- and foreign-born blacks in New York City

BACKGROUND

Research examining the association of residence in racially segregated neighborhoods with physical and mental health outcomes among blacks is mixed. Research elucidating the relationship between segregation and hypertension has been limited. This study examines the association between segregation and hypertension among US- and foreign-born blacks in New York City (NYC).

METHODS

Individual-level data from the NYC Community Health Survey (n = 4,499) were linked to neighborhood-level data from the US Census and Infoshare Online. Prevalence ratios (PRs) for the association between segregation and self-reported hypertension among US- and foreign-born blacks were estimated.

RESULTS

After adjusting for individual- and neighborhood-level covariates, segregation was not associated with hypertension among US-born blacks or foreign-born blacks under 65 years of age. Older foreign-born blacks in highly segregated areas had a 46% lower probability (PR = 0.54; 95% confidence interval, 0.40-0.72) of reporting hypertension than older foreign-born blacks residing in low segregation areas.

CONCLUSIONS

In this NYC-based sample, no association between segregation and hypertension was observed among US-born or younger foreign-born blacks; however, our results suggest possible benefits of segregation for older foreign-born blacks. Further studies should determine whether this association is observed in other cities and identify factors that may mitigate against the adverse effects of segregation.

Sodium, blood pressure, and ethnicity: what have we learned?

An enormous amount of research has yielded significant knowledge about ethnic differences in sodium homeostasis and blood pressure regulation. Consistent findings such as greater sodium-sensitivity, lower potassium excretion and high higher serum sodium levels in African Americans need further exploration to define more precise physiological mechanisms. The genetic alleles associated with sodium homeostasis in relation to blood pressure have accounted for only a small proportion of the variance in blood pressure. Several allelic variants differ in frequency among ethnic groups and heat-adapted genetic variants have a high prevalence in low latitudes and hot, wet climates which lends support to the "sodium retention" hypothesis. The blood pressure disparities between African Americans and whites may, in part, be due to different allelic frequencies of genes associated with sodium homeostasis. However, with advances in genomics, environmental factors tend to be neglected in research. Better measures of environmental stress have recently been developed by anthropologists and should be included in research designs by investigators in other disciplines. Public health efforts should encourage food producers to reduce sodium content of its products, and physicians should encourage patients to reduce consumption of high sodium packaged and fast foods.

Genetic and environmental risks for high blood pressure among African American mothers and daughters

OBJECTIVE

To determine the relationship between genetic and environmental lifestyle factors (physical activity and sodium) on blood pressure (BP) among African-American women.

METHOD

In this cross-sectional study involving 108 African-American mothers and daughters from a Midwestern area, investigators obtained BP measurements, information on minutes of physical activity, amount of sodium intake, and buccal swab saliva samples.

RESULTS

Of the 4 single nucleotide polymorphisms (SNPs) on the sodium bicarbonate cotransporter gene (SLC4A5), rs8179526 had a statistically significant interaction with cytosine/thymine (C/T) genotype by sodium status on systolic BP (SBP; p=.0077). For gene x physical activity interaction, 2 significant interactions (cytosine/adenine [C/A] genotype by physical activity and adenine/adenine [A/A] genotype by physical activity, p=.0107 and p=.0171, respectively) on SBP and 1 on diastolic BP (DBP; A/A genotype by physical activity, p=.0233) were found on rs1017783. Two significant guanine/adenine [G/A] genotype by physical activity interactions were found on rs6731545 for SBP and DBP (p=.0160 and p=.0492, respectively).

DISCUSSION

A gene x environmental interaction with rs8179526 has a protective effect on SBP in African-American women with high sodium intake. Participants with C/T genotype of rs8179526 who consumed greater than 2,300 mg of sodium had lower SBP than those who consumed less than recommended. Women with thymine/thymine (T/T) genotype of rs8179526 who consumed greater than 2,300 mg had lower SBP than those who consumed less. Awareness of both the protective and deleterious properties of rs8179526 in African-American women may one day assist in determining appropriate treatment plans.

The management of hypertension in African Americans

The prevalence of hypertension in blacks in the United States is among the highest in the world. Compared with whites, blacks develop hypertension at an earlier age, their average blood pressures are much higher and they experience worse disease severity. Consequently, blacks have a 1.3 times greater rate of nonfatal stroke, 1.8 times greater rate of fatal stroke, 1.5 times greater rate of heart disease death, 4.2 times greater rate of end-stage kidney disease, and a 50% higher frequency of heart failure; overall, mortality due to hypertension and its consequences is 4 to 5 times more likely in African Americans than in whites. The increased prevalence of hypertension and excessive target organ damage is due to a combination of genetic and, most likely, environmental factors. There are no clinical trial data at present to suggest that lower-than-usual BP targets should be set for high-risk demographic groups such as African Americans. The primary means of prevention and early treatment of hypertension in African Americans will be the appropriate use of lifestyle modification. The International Society of Hypertension in Blacks guidelines realize that most patients will require combination therapy, many of them first-line, to reach appropriate BP goals. Although certain classes and combinations of antihypertensive agents have been well-established to be effective, the choice of drugs for combination therapy in African American patients may be different. Within the African American group, the responsiveness to monotherapy with ACE inhibitors, angiotensin receptor blockers, and beta blockers may be less than the responsiveness to diuretics and calcium channel blockers, but these differences are corrected when diuretics are added to the neurohormonal antagonists. Of note, African American patients with systolic BP >15 mm Hg or a diastolic BP >10 mm Hg above goal should be treated with first-line combination therapy.

Haplotype diversity in four genes (CLCNKA, CLCNKB, BSND, NEDD4L) involved in renal salt reabsorption

OBJECTIVE

Differences exist among various populations with regards to hypertension prevalence, severity, progression and response to therapy. Such differences may be due to genetic or environmental factors. We characterized the genetic variation and haplotype diversity of four hypertension candidate genes (CLCNKA, CLCNKB, BSND, NEDD4L) in four different ethnic groups (Caucasian Americans, African-Americans, Han Chinese, and Mexican-Americans).

METHODS

We genotyped 42 single nucleotide polymorphisms across the four genes in equal numbers of each ethnically defined population, then tested for linkage disequilibrium, computed allelic and haplotype frequencies, and compared data across the different ethnic groups.

RESULTS

We identified significant genotype and allele frequency differences among ethnic groups. The strongest differences were observed between African-American and Mexican-Americans and between Caucasian and Mexican-Americans. In addition, haplotype blocks were defined for BSND, CLCNKA_B and NEDD4L in the four populations examined. Completely mismatched ('yin yang') haplotypes were also observed. We found that the number of inferred halpotypes varied gene to gene and in some instances between the populations for a given gene indicating substantial haplotype diversity. The haplotype diversity among the various ethnic populations observed in our study was greater than that reported in Perlegen database.

CONCLUSIONS

Haplotype diversity in hypertension candidate genes has important implications for designing and evaluating candidate gene or genome-wide blood pressure association studies that consider these genes.

Enhanced nephrogenesis in offspring of water-restricted rat dams

OBJECTIVE

Maternal water restriction (WR) may induce offspring plasma hypertonicity and enhanced vasopressin secretory responses. We determined effects of pregnancy WR on offspring body composition, renal morphology, and blood pressure.

STUDY DESIGN

Pregnant Sprague Dawley rats (n = 21) were randomized to WR, pair-fed (PF), and control from embryo day (e) 10 to e21. Offspring body and organ weights and glomerular number and size were measured at birth and at 21 days of age. At 6 and 9 weeks, offspring blood pressure was determined.

RESULTS

At 21 days of age, WR offspring glomerular number was increased (17%; P < .05), whereas PF glomerular number was lower (4%), compared with controls. Systolic blood pressures were elevated in both WR and PF at both 6 and 9 weeks.

CONCLUSIONS

Pregnancy WR stimulates offspring nephrogenesis, suggesting an adaptive response to future dehydration. Programmed hypertension in WR and PF groups likely occurs via different mechanisms.

Fixed combination isosorbide dinitrate–hydralazine for nitric-oxide-enhancing therapy in heart failure

The major advances in our understanding and management of heart failure (HF) in recent decades have not fully benefited all segments of our population. HF still represents a growing epidemic, especially for African-Americans, in whom the burden of HF is even greater. The recently reported beneficial effects of the fixed combination of isosorbide dinitrate and hydralazine (ISDN+HYD) in the African-American Heart Failure Trial (A-HeFT), has led to both the FDA approval of this agent and its endorsement by the latest HF guidelines. The properties of ISDN+HYD are well known as its components are mature agents, readily available in generic formulations that have been used for decades in other indications. However, fixed-dose ISDN+HYD represents the first drug to undergo targeted clinical development and to be approved for use in a specific ethnic group. As such, A-HeFT and the approval of ISDN+HYD represent landmark events that merit further scrutiny.

Skin color, social classification, and blood pressure in southeastern Puerto Rico

OBJECTIVES

We tested competing hypotheses for the skin color-blood pressure relationship by analyzing the association between blood pressure and 2 skin color variables: skin pigmentation and social classification.

METHODS

We measured skin pigmentation by reflectance spectrophotometry and social classification by linking respondents to ethnographic data on the cultural model of "color" in southeastern Puerto Rico. We used multiple regression analysis to test the associations between these variables and blood pressure in a community-based sample of Puerto Rican adults aged 25-55 years (n=100). Regression models included age, gender, body mass index (BMI), self-reported use of antihypertensive medication, and socioeconomic status (SES).

RESULTS

Social classification, but not skin pigmentation, is associated with systolic and diastolic blood pressure through a statistical interaction with SES, independent of age, gender, BMI, self-reported use of antihypertensive medication, and skin reflectance.

CONCLUSION

Our findings suggest that sociocultural processes mediate the relationship between skin color and blood pressure. They also help to clarify the meaning and measurement of skin color and "race" as social variables in health research.

Hypertension in black patients: Special issues and considerations

The excess risk for hypertension in black Americans continues to be a major health concern. Although there is considerable information regarding these disease trends, many of the major underpinnings of the etiology of hypertension remain unclear. The excess mortality in blacks due to heart disease, renal failure, and stroke is clearly directly related to the excess burden of hypertension. Amid the recent findings about the pathophysiology of hypertension, some clear differences in the effects of overweight, salt sensitivity, and vascular biology emerge along ethnic lines. These differences may shed some light on the development of more effective treatment strategies. Based on our current knowledge, aggressive management of hypertension in blacks is critical. This review highlights what is known about various factors affecting hypertension and its treatment in black Americans.

Skin pigmentation, self-perceived color, and arterial blood pressure in Puerto Rico

Darker skin color has been associated with higher average blood pressure in several African-derived populations in the Americas. This pattern has been interpreted as evidence of genetic, physiologic, or sociocultural mechanisms, but existing evidence does not provide an adequate means of evaluating these alternatives. This paper introduces a measurement strategy to isolate the cultural and biological dimensions of skin color, and it develops a specific hypothesis regarding the cultural significance of skin color in Puerto Rico and its relationship to arterial blood pressure. Data come from a face-to-face survey in southeastern Puerto Rico (N = 100). There is no association between blood pressure and skin pigmentation, as measured by reflectance spectrophotometry. However, the discrepancy between self-perceived color and skin pigmentation, a measure we call "color incongruity," is associated with systolic blood pressure (SBP) through an interaction with socioeconomic status (SES) (P = 0.009). For low-SES respondents, darker self-ratings of color relative to skin pigmentation are associated with higher mean SBP. For high-SES respondents, however, darker self-ratings of color relative to pigmentation are associated with lower mean SBP. We interpret this pattern as evidence that the relationship between skin color and blood pressure is mediated by sociocultural processes, and we highlight the need for testable hypotheses and appropriate measurement operations in research on racial inequalities in health.

Hypertension in black patients: special issues and considerations

The excess risk of hypertension in black Americans continues to be a major health concern. Although there is considerable information regarding these disease trends, much of the major underpinnings of the etiology of hypertension remain unclear. The excess mortality in blacks due to heart disease, renal failure, and stroke are clearly directly related to the excess burden of hypertension. Amid the recent findings about the pathophysiology of hypertension, some clear differences in the effects of overweight, salt sensitivity, and vascular biology emerge along ethnic lines. These differences may shed some light on the development of more effective treatment strategies. Based on our current knowledge, aggressive management of hypertension in blacks is critical. This review highlights what is known about various factors affecting hypertension and its treatment in black Americans.

The prevention of heart failure in minority communities and discrepancies in health care delivery systems

This article discusses risk factors for cardiovascular disease in the minority community, including hypertension, obesity, diabetes,and diet. The minority community exhibits important population differences regarding risk and outcomes for cardiovascular disease. The complete explanation for these differential outcomes is lacking and likely to be multifactorial in origin; however, disparities in health care (differences in the quality of health care that are not due to access-related factors or clinical needs, to preferences, or to the appropriateness of the intervention) may emanate from decisions made by the patient, provider, or health care system. Hypertension as a disease entity is strikingly pathologic in African Americans. Correspondingly, the incidence of cardiovascular mortality due to hypertensive heart disease is fourfold higher in African Americans than in non-Hispanic whites. Hypertension and heart failure can be treated effectively in the minority community with a regimen of agents not dissimilar from that used for the general population. Treatment regimens should be individualized based on the disease presentation, associated comorbidity, and disease severity and not on something as arbitrary as race.