An evolving picture: hypertension in African-Americans

An evolving picture: hypertension in African-Americans

Charlotte Szromba

Hypertension prevalence among African-Americans in the United States is 50% greater than among Caucasians. Studies from the past 40 years have recognized that hypertension is a different phenomenon in the African-American population. It is more complex; difficult to manage; and causes more severe complications such as cardiovascular disease, atherosclerosis, left ventricular hypertrophy, and kidney disease. In fact, African-Americans are four times more likely than Caucasians to progress to end stage renal disease (ESRD).

Managing hypertension in African-Americans is complex and multi-faceted with several unique aspects to consider. Recent studies have proposed multiple biological explanations for the hypertension including enhanced salt sensitivity, insulin resistance, and vascular hyperresponsivity to adrenergic stimuli. However, these factors only partially explain the increased prevalence of hypertension in African-Americans. Many studies have examined the potential influence of social and psychological factors in relation to cultural and historical influences in the community on the risk for hypertension. Current studies are analyzing the effect of obesity and risk for cardiovascular disease. So the picture of hypertension in African-Americans continues to change and evolve with time and the additional information from new studies. The studies chosen for review in this journal club were selected because they highlight a multi-faceted approach to hypertension in the African-American population.

Bergman, S., Key, B., Kirk, K., Warnock, D., & Rostand, S. (1996). Kidney disease in the first-degree relatives of African-Americans with hypertensive end stage renal disease. American Journal of Kidney Diseases, 27(3), 341-346.

Summary: The purpose of this study was to investigate familial risk of renal disease in African-American dialysis patients and their first-degree relatives in a county in Alabama. During a 9-month period of time, 472 African-American dialysis patients were reviewed and screened to determine the cause of ESRD. With the application of strict criteria, 85 index cases (first cases identified within a family) of ESRD associated with hypertension were identified. A final index group of 38 men and 37 women agreed to participate in the study. Of these 75 final index cases, 40 had participating family members, which resulted in a total of 103 first-degree relatives enrolled in the study. Hypertension was found in each of the 40 families in the study (100%). Diabetes mellitus was present in 24 of the 40 participating families (60%). This finding is somewhat surprising since diabetes was an exclusion factor in the 75 index cases. However, it supports the close association of hypertension and insulin resistance in some individuals.

The researchers also examined available first-degree family members for early signs of nephropathy. First-degree relatives included parents, full siblings, and offspring. The results indicated that 26 of 40 (6.5%) participating families had at least one person with signs of nephropathy. Other studies support the familial clustering of nephropathy in African-Americans with diabetes mellitus and hypertension. The researchers found that there is a strong concurrence of renal disease in the families of African-Americans with hypertensive ESRD, suggesting that the parents, siblings, and offspring are at great risk for developing renal disease.

Commentary: This study involved a small number of patients in a specific county in Alabama. However, studies in other parts of the country, specifically California and North Carolina, support the findings. Nephrology nurses have frequent contact with African-American first-degree relatives of hypertensive and diabetic ESRD patients.

Expanding the scope of care to these relatives and urging visits to health care providers can provide for identification and management of those at risk for the development of renal disease. Informal monitoring of the blood pressure of these relatives during visits to renal or dialysis clinics provides an opportunity to begin a dialog on the importance of monitoring and follow-up care for African-Americans at risk for renal disease.

Dressler, W. (1996). Hypertension in the African-American community: Social, cultural, and psychological factors. Seminars in Nephrology, 16(2), 71-82.

Summary: This research review article examined the cultural and historical processes that determine the nature of expectations, life opportunities, and daily interactions in the African-American community in American society. It attempted to grasp the ways in which being of African descent in modern day America shapes a person’s life. Several concepts were examined including cultural and socioeconomic factors, social change in the community, “John Henryism,” social mobility, socioecologic stress, experience of anger, and social resources in relation to hypertension in African-Americans.

In American society, the risk of hypertension is higher among persons in lower socioeconomic status as measured by the level of education, occupation, and income. Studies demonstrate an inverse relationship between socioeconomic status and hypertension prevalence. The hypothesis of “status incongruence” has been studied in Mexico, St. Lucia, Jamaica, and Brazil and has also been researched in African-American communities in the rural South. Status incongruence refers to the discrepancy between an individual’s lifestyle and economic status. The civil rights movement has led to changing lifestyle aspirations in the African-American community. Individuals want equal participation in American society in terms of economics, politics, and adoption of consumer lifestyles. The problem in the African-American community is that these aspirations remain unfulfilled, since the economic gap between blacks and whites in America is substantial. This model was studied in a small Southern city, where 186 individuals aged 25 to 55 participated. A 23-item index that assessed ownership of consumer goods and exposure to information was used to measure lifestyle. Economic status was measured by an index that combined occupation, education, and income. Status incongruence was measured by examining the degree to which the individual’s ranking on lifestyle differed from their own socioeconomic ranking. The results indicated that those individuals with a low degree of status incongruence had a 9.8% prevalence of hypertension. Those with a moderate amount had a hypertension prevalence of 12.6% Those with the highest level of status incongruence had a 32.8% prevalence rate.

The hypothesis of “John Henryism” was explored in a study by Sherman James. This concept is based on a mythical black steeldriver who challenged a machine to a contest. It is a belief system regarding hard work and individual responsibility, that is, “I can accomplish anything with hard work and my own efforts.” James studied this concept and its effect on mean blood pressure. In one study, those African-Americans who were high on the John Henryism scale but low on economic resources had a prevalence of hypertension of 31.4%. Those with a high score on John Henryism and high on economic resources were 11.5%. For individuals low on the John Henryism scale, the prevalence of hypertension was 24.0%, regardless of economic ratings.

The concept of socioecologic stress was also studied in Detroit neighborhoods. In this hypothesis, socioecologic stress was defined as living in a neighborhood characterized by low socioeconomic status and high social instability. In this environment, an individual is faced with a high level of unpredictability combined with fewer resources for coping. As hypothesized, individuals in these areas had higher blood pressures. There is growing evidence from numerous studies that the experience of anger, either its suppression or expression, is associated with not only hypertension but also cardiovascular disease. Many studies support this hypothesis, including one conducted in Detroit with African-American men. Those who lived in high stress areas who reported feeling anger but did not express it, in response to arbitrary aggression, were two times as likely to have high blood pressures than persons who expressed anger (33% vs. 16%).

Numerous studies support the concept that social support can decrease the risk of disease. In the African-American community, it is not surprising that church membership is an important component of social support and integration given the central role it has historically played. The economic marginality after slavery raised the importance of the extended family as a means of social support in the African-American community.

Commentary: This research review article emphasizes the social, cultural, and psychological factors that impact on the risk of hypertension in African-Americans living in modern day America. The studies reviewed here emphasize the subjective emotional experience of individuals and its relationship to blood pressure. The studies are consistent because each emphasizes the chronic struggle against difficult odds that African-Americans encounter on a daily basis. Increasing awareness of these factors by health care providers can hopefully lead to better care for African-Americans. Behavioral interventions, such as stress reduction training or biofeedback, need to be studied for their effectiveness in this population. Nephrology nurses are in a position to create and conduct such studies.

This article also indicates that there are unique strengths in the African-American community that help to buffer the impact of these social, cultural, and psychological factors. The church and the extended family are recognized supports and should be acknowledged and incorporated into the care of the African-American individual.

Smith, E. (1992). Hypertension management with church-based education: A pilot study. Journal of National Black Nurses Association, 6(1), 19-28.

Summary: The purpose of this study was to examine the effectiveness of an educational intervention for individuals with hypertension attending African-American churches. The subjects, 29 females and 3 males, were from three inner city Black churches. The intervention was carried out in two phases. In phase one, six registered nurses from the American Heart Association of Metropolitan Chicago were prepared as educational experts using a 16-hour course. The nurses then worked in pairs to implement the educational intervention, which consisted of five 90-minute weekly educational sessions. Topics included understanding hypertension, diet, drug therapy, stress management, and roles and responsibilities in management of hypertension.

The measurement instrument used in the study was the Hypertensive Patient Data Record, which included information on hypertensive history, risk factors, and prescribed treatment. Section two of the instrument examined the individual’s self-assessment of health and stress, while section three provided self-report on sodium intake. Knowledge was measured with the Hypertension Knowledge Test and social support was measured with the Social Support Network Inventory. Data were collected from subjects in face-to-face interviews prior to the intervention (pre), immediately after the intervention (post#1), and 3 months later (post#2). Results indicated a significant difference in knowledge means between pre and post#1 (n = 18; t + 26.65; df + 17; p = <.001) and post #2 (n = 8; t = 14.97; df= 7; p = <.0001). No significant changes were found in blood pressure readings and sodium intake.

Commentary: This study utilized an innovative community or church-based approach to reach African-Americans with hypertension. Other similar studies have concentrated on weight loss and its effect on blood pressure in comparable settings. Although no significant differences were noted in blood pressure readings or sodium intake, knowledge was increased as a result of the intervention. Knowledge may influence how individuals appraise a chronic illness such as hypertension and may urge them to look at individual adaptive strategies. This study should be replicated with a larger sample, and data should be collected for a longer period of time to detect meaningful behavioral changes after educational interventions.

Wagner, L. (1998). Hypertension in African-American males. Clinical Excellence for Nurse Practitioners, 2(4), 225-231.

Summary: This clinical study outlines some of the special concerns related to the management of hypertension in African-Americans using a case study of a 55-year-old male. The author discusses five key components of care: physiological differences, social economic status, education, relationship to health system, and other social and psychological aspects. Racial differences in pathophysiology of hypertension include decreased renal blood flow, increased vascular resistance, altered plasma reninangiotensin-aldosterone system, and high intracellular sodium levels. Socioeconomic status may determine access to and use of health care resources, ability to pay for medications, transportation difficulties, ability to follow prescribed diet, and lifestyle modifications.

The author proposes that the choice of pharmacologic treatment should be made with consideration of comorbidities, side effects of medications, and documented efficacy of medications for African-Americans. Diuretics and calcium channel blockers ate recommended. Monotherapy with beta-blockers of angiotensin converting enzyme (ACE) inhibitors ate usually not as effective. New combination medications may work well in this population. Side effects of medications can discourage good compliance and practitioners ate urged to monitor and discuss possible side effects at the start of therapy, with a suggestion for a phone call to discuss concerns before discontinuing the medication.

The author recommends encouragement of specific lifestyle changes for hypertension management. Salt restriction (2-4 g/d) appears to be particularly efficacious with African-Americans and is associated with a drop in blood pressure of 4.9/2.6 mmHg. Studies of the effects of exercise on blood pressure in African-American men reported a lower blood pressure and decrease in left ventricular mass for those who exercised. Another study found meditation and progressive relaxation to be effective stress-reduction methods in African-Americans.

The author also recommends that the practitioner learn about the patient’s beliefs and values. One study demonstrated that African-Americans were usually found to be present-oriented versus future-oriented. Individuals felt less susceptible to the consequences of hypertension and believed in the value of home remedies instead of prescribed medications. In another study, African-Americans were more likely than their white counterparts to accept higher diastolic pressures as normal, which might affect their management. Culturally and educationally appropriate teaching materials that emphasize preventive measures and follow-up care rather than crisis-oriented intervention should be used.

Finally, the author proposes that health care providers should consider the informal support systems of African-Americans and include these in the plan of care. Studies indicate that African-Americans rely on family, friends, neighbors, and church groups to counteract socioeconomic and psychological stressors.

Commentary: The author presented a well-organized overview of important points to consider when caring for African-Americans with hypertension. Several pertinent study findings involving African-Americans were reported that may influence care in this population. The case study format provides a framework for application of findings to nursing practice. This clinical study appeared in a publication for nurse practitioners, lending credence to the belief that advanced practice nurses can manage patients with chronic disease in a manner that is culturally appropriate and centered on the patient.

Weir, M., & Hanes, D. (1996). Hypertension in African-Americans: A paradigm of metabolic disarray. Seminars in Nephrology, 16(2),102-109.

Summary: The emphasis in this discussion article is on the metabolic processes that contribute to hypertension in African-Americans. Numerous clinical studies have shown that hypertension in African-Americans has several clinical characteristics including occurrence at an earlier age with greater frequency and intensity, obesity, greater prevalence of hypertensive nephrosclerosis, non-insulin dependent diabetes, and stress. Several studies suggest that insulin resistance may precede and, possibly, predict the development of hypertension in African-Americans and other ethnic groups studied. Clinical studies support the relationship between obesity and insulin resistance, with evidence that weight loss improves tissue insulin sensitivity. Obesity is disproportionately prevalent in African-Americans, especially African-American women, contributing to the development of hypertension. Pathophysiological characteristics contributing to hypertension in African-Americans include salt sensitivity, enhanced vascular responsiveness to adrenergic stimuli, and increased systemic and renal vascular resistance. Hypertensive African-Americans ate disproportionately salt sensitive when compared to other groups. Glomerular hemodynamic changes exaggerate salt and water retention by the kidneys and accelerate the hypertensive process. Some studies provide a theoretical link between salt sensitivity and insulin resistance. This link may also explain the increase in vascular response to adrenergic stimuli leading to a higher incidence of hypertension in African-Americans.

Commentary: In this article, the authors attempt to weave together clinical observations and pathophysiological characteristics of hypertension in African-Americans. Insulin resistance as a central factor in the metabolic disarray that occurs in hypertensive African-Americans is the main point of this article. Further study is needed to examine the efficacy of various therapeutic interventions in decreasing insulin resistance in African-Americans. To effectively treat hypertension in African-Americans, the practitioner must be aware of all factors that impact on the disease process.

Additional Readings

He, J., Klag, M., Appel, L., Charleston, J., & Whelton, P. (1999). The renin-angiotensin system and blood pressure: Differences between blacks and whites. Journal of Hypertension, 12(6), 555-562.

Hill, M., Bone, L., Hilton, S., Roary, M., Kelen, G., & Levine, D. (1999). A clinical trial to improve high blood pressure care in young urban black men: Recruitment, follow-up, and outcomes. American Journal of Hypertension, 12(6), 548-554.

Jones, D. (1999). What is the role of obesity in hypertension and target organ injury in African Americans? The American Journal of Medical Sciences, 317(3), 147-151.

Kumanyika, S., & Charleston, J. (1992). Lose weight and win: A church-based weight loss program for blood pressure control among black women. Patient Education and Counseling, 19, 19-32.

Lackland, D., & Keil, J. (1996). Epidemiology of hypertension in African Americans. Seminars in Nephrology, 16(2), 63-70.

Charlotte Szromba, MSN, RN, CS, CNN, is a certified adult nurse practitioner, Section of Nephrology at the University of Chicago Hospitals, Chicago, IL.

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