Blacks suffer disproportionably from hypertension (HTN), and rates in African Americans compared with whites are among the highest in the world.1,2 Based on data from 1960 to 1991, approximately 30% of African American men and women have HTN compared with 20% of all Americans.3 It is estimated that 30% of all cardiovascular diseases (CVD) can be attributed to HTN. As a result, uncontrolled HTN is a key factor in understanding ethnic differences in CVD.1,3 Recognition of the disproportionate rate of HTN in African Americans resulted in it being targeted as a high-priority national health objective.4-6
Although HTN is more prevalent in African American men, it is of significant concern among African American women. Rates of premature death from CVD in 1992 were more than double for African American women compared with white women (274 per 100,000 compared with 107 per 100,000, respectively).3 Clearly, African American women are at greater risk for CVD, and this may be associated with uncontrolled HTN. Although many factors relate to uncontrolled HTN in this population, access to a regular continuous source of care may be far more significant than realized because such a source of care is a prerequisite to early diagnosis and successful management of this chronic condition.7 Understanding those factors that impede or facilitate access to regular continuous care for African American women with HTN will provide the information needed to promote adequate use of healthcare services and, ultimately, treatment adherence.
Despite the importance of adherence to treatment in HTN management, there have been few attempts to incorporate likely or known indicators of adherence to HTN treatment in a theoretical model that can be used to guide research and practice. The adapted Hill-Levine model (Figure 1) offers an appropriate framework for studying these phenomena in African American women because factors frequently associated with seeking and using healthcare services are organized in three dimensions, including predisposing, enabling, and reinforcing factors. Organizing the factors related to adherence to treatment according to the Hill-Levine framework elucidates the various roles that patients, providers, and healthcare systems must play for hypertensive African American women to achieve recommended levels of blood pressure control.8
The purpose of this article is to (1) discuss the magnitude of the problem presented by HTN and the lack of HTN control in African American women, (2) identify from the literature the factors related to adherence to treatment in HTN management in general and in African American women specifically, and (3) use the Hill-Levine9,10 model to organize the identified predisposing, enabling, and reinforcing factors associated with adherence to HTN treatment recommendations among African American women.
Problem and Significance of HTN among African American Women
There is an epidemic of HTN among African American women, with 45% of African American women compared with 30% of white women affected nationwide.11 In addition, HTN portends greater morbidity and mortality among African American women than among whites or other minorities.11 Specifically, mortality rates from stroke in 2001 were 74% in African American women compared with 54% in white women.11 The risk of end-stage renal disease (a complication of HTN) is at least fourfold greater in African Americans than in whites.12 African Americans represent 32% of all treated end-stage renal disease patients.11,13 The number one killer of women who are older than 40 years is coronary heart disease (including heart attack and angina pectoris), another complication of HTN.14 Coronary heart disease is more prevalent in African American women (9%) than in African American men (7%).10,11
Despite current advances in disease management, African American women continue to suffer from a higher incidence and prevalence of HTN compared with other ethnic and sex groups.15 The Institute of Medicine16 reports extensive racial disparities in quality of care and outcomes. The reason for these disparities is not well understood. Kotchen et al7 report that 74% of African American women had uncontrolled blood pressure even though 64% reported having seen a physician in the previous months.
Factors Related to Treatment Adherence
Recent clinical trials indicate that blood pressure control can be achieved in most patients.17Table 1 shows the blood pressure targets according to the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: JNC-VII.6,11,17 Numerous studies have shown that blood pressure control cannot be achieved without adherence to recommended treatment regimens.10,18-20
For anyone with HTN, adhering to an anti-HTN regimen includes motivation to take prescribed medications and establish and maintain a health-promoting lifestyle.17,21 About 64% of individuals who take HTN medications fail to achieve therapeutic benefits because they do not adhere sufficiently to the prescribed regimen.22 Factors influencing nonadherence include lack of knowledge about the disease, medication side effects, and socioeconomic (lack of insurance) and cost factors.23 Ogedegbe et al24 found four categories of barriers to adherence: patient specific (eg, forgetfulness), medication specific (eg, side effects), logistic (eg, getting refills), and disease specific (eg, asymptomatic nature of HTN). In general, facilitators of adherence included the use of reminders; having a routine; knowledge about HTN, its treatment and complications; having social support; and good physician-patient communication.
In the study to understand the experiences of living with HTN among African American hypertensive men, Rose et al25 concluded that adherence is multifaceted and dynamic, depending upon social, economic, and personal circumstances, that empathetic and nonjudgmental assistance from providers is needed, and that financial concerns and employment and drug addiction status need to be considered. Most studies have included African American men; studies to elucidate interventions for African American women with HTN remain unclear. Although Morisky et al26 recommended an urgent need for effective blood pressure management strategies in African American women more than two decades ago, little progress has been made.
Specific Factors Related to Treatment Adherence in African American Women
There is a paucity of clinical research delineating the factors related to adherence to treatment recommendations among African American women. Clinical investigations that included African American women found a need for effective HTN management and increased access to healthcare.3,10,27,28 In a study including African Americans and whites, Jones et al27 found that the average age-adjusted incidence rates for coronary heart disease were higher for African American women than for white women. They concluded that HTN was a particularly strong risk factor in African American women and that aggressive management of traditional risk factors was needed. Collins and Winkleby3 also conducted another study on African Americans at high and low risk for HTN and found that individuals at risk for uncontrolled blood pressure were more likely to be women with low level of education, not on antihypertensive medications, and distinguished by infrequent contact with a physician. Collins and Winkleby3 concluded with the need for effective HTN management and increased access to healthcare for high-risk African Americans. Shea et al28 examined the correlates of nonadherence to HTN treatment in an inner-city minority population including African Americans. Dichotomizing self-reported nonadherence information as more or less adherent, they found that nonadherence was associated with having blood pressure checked in an emergency room, lack of a primary care physician, current smoking, and younger age. Shea et al concluded that changing the locus of care for HTN from emergency rooms to primary care physicians might improve adherence to HTN treatment in minority groups.
Several other factors, such as a regular source of healthcare, the use of emergency room services, episodic or fragmented healthcare, lack of follow-up, and the high cost of treatment, have been shown to interfere with effective blood pressure control.2,28 Emergency room care is associated with lack of follow-up (a requirement for the management of a chronic disease like HTN) and higher cost for services used. Likewise, public hospital emergency center users represent a group at risk for undertreatment of HTN.2 Hyman et al2 concluded that improvement in HTN control among African Americans would depend on changes in diagnosis and management practices of healthcare providers and on the maintenance of primary care access for all socioeconomic groups.
In African American men, lifestyle risk factors predicting adherence to prescribed regimens included being in HTN care, alcohol use (past and present), illicit drug use, cigarette smoking, and dietary practices.9 Current literature suggests that hypertensive African American women might have similar issues. However, there is a paucity of information regarding lifestyle factors that influence the ability to access care, remain in care, and adhere to recommended regimens of hypertensive African American women.9,29
Evidence-based interventions for urban hypertensive African Americans have been tested only recently. Using the Hill-Levine model (nurse practitioner- community health worker-physician framework), which examines predisposing, enabling, and reinforcing factors to adherence to HTN treatment, in young hypertensive African American men, Hill et al30 reported blood pressure control at 44% in the intervention group versus 31% in the control group. In a study of African Americans, Artinian et al1 tested the hypothesis that those who participate in nurse-managed home telemonitoring plus usual care or participate in nurse-managed, community-based monitoring plus usual care will have greater improvement in blood pressure from baseline to 3-month follow-up than will those who receive usual care only. They found that both the home telemonitoring group and the community-based monitoring group had clinically and statistically significant (P < .05) drops in systolic and diastolic blood pressure at 3-month follow-up. The results from the Hill et al30 and Artinian et al1 studies indicate that innovative approaches to control blood pressure in African Americans can yield positive results.
Among effective interventions, the role of cultural relevance and community participation in intervention design are emerging concepts that are gaining support among scholars and researchers.10 Effective interventions for urban hypertensive African Americans need to be culturally relevant and should allow participation by the indigenous population in the development, intervention, and evaluation of interventions.10 The latter is not being done, and barriers to effective management of HTN and specific strategies in African American women remain unclear. Oliver- McNeil and Artinian14 conducted a study in 33 white women newly diagnosed with HTN and concluded that women with coronary heart disease may not know what risk factors they have and may require thorough risk assessment and counseling. But the conclusions are applicable to any diagnosed hypertensive patient regardless of ethnicity. Studies that explore knowledge on personal CVD risk factors and adherence to treatment of HTN in African American women are urgently needed.
Application of the Hill-Levine Model
The Hill-Levine model, adapted from Green and Krueter's31 PRECEDE-PROCEED (acronym for predisposing, reinforcing, and enabling causes in educational diagnosis and evaluation) model, addresses multiple barriers that affect one's ability and willingness to stay in care and follow a prescribed HTN regimen. The model combines public health and medical models and integrates health education, behavior change, and maintenance principles with culturally sensitive approaches, social action, and social learning theory. The Hill-Levine model provides the framework for conceptualizing individual factors that positively or negatively (eg, barriers) affect adherence behaviors that lead to health outcomes (predisposing, enabling, and reinforcing). Predisposing factors assess knowledge, beliefs, and attitudes about HTN. Enabling factors assess healthcare access, health behavior skills, health status, and lifestyle. Reinforcing factors, such as social support and supportive services, assess living arrangement and social isolation.
The Hill-Levine model is a nurse practitioner- community health worker-physician model. The model supports the use by a multidisciplinary team of comprehensive and individualized interventions with demonstrated effectiveness in controlling blood pressure in hypertensive African American men.9 In this model, predisposing, enabling, and reinforcing factors in adherence to HTN treatment in African American men were examined.9Figure 1 is adapted from the Hill model for the purpose of examining adherence to HTN treatment recommendations. An implication from the Hill study is to describe the relations between adherence factors and blood pressure. Levine et al10 used an adapted Hill model of the nurse-supervised indigenous community health worker intervention process in a clinical trial with urban African Americans (62% women). These authors reported a significant decrease in mean systolic and diastolic pressures (P < .05) and an increase in the percentage of individuals with controlled blood pressure (baseline to 40-month follow-up). Although the study results of Levine et al complemented prior studies,32,33 differences between a more intensive versus less intensive intervention were not statistically significant. Moreover, Levine et al s study was not sex focused. Identifying African American women's barriers to adherence to HTN treatment and revising Levine's intervention process accordingly could enhance the potential impact of interventions among this important subgroup.
In the Hill-Levine model, predisposing factors include knowledge, beliefs, and attitudes. Knowledge on HTN is significantly related to its prevalence and to adherence to treatment.34,35 Using street intercept interviews and 12 focus group interviews, Wilson et al35 investigated how lay beliefs of low- to middle-income urban African American communities regarding HTN diverge from current medical understanding. Results indicated that 35% of respondents (men and women) related HTN to eating pork or food that makes blood travel fast to the head (consistent with "high blood"). Only 15% related HTN to increased pressure in the blood vessels. In contrast, focus group data indicated that HTN was (a) believed to be linked to eating pork in 8 of 12 groups; (b) perceived as a symptomatic illness in all 12 groups; and (c) considered treatable with vitamins, garlic, and other herbs in 11 groups. Of the 12 groups, 10 reported that HTN was linked to prescribed medications, whereas 8 groups believed that lifestyle modification, including weight loss, was important in HTN. Wilson et al concluded that dominant African American beliefs diverged sharply from current medical understanding. Similarly, Lukoschek36 found that both male and female African Americans held a variety of divergent beliefs regarding antihypertensive medications. These included perceiving medication as harmful and ineffective and expressing distrust of pharmaceutical companies and physicians (ie, believing them to use patients for experimentation to test medications).
Demographic characteristics are included as predisposing factors in the model and include educational level, income, and age. Initial evidence indicates that lower education and advanced age are associated with greater nonadherence to treatment of HTN among African Americans. Specifically, African American women at risk for uncontrolled HTN have been reported to be less educated than those whose blood pressure was better regulated. In addition, the middle or older aged and less educated women had the highest rate of HTN.3
The Hill-Levine model describes enabling factors as access to healthcare resources and health behavior skills. These variables have been operationalized as the presence or absence of the following: health insurance, a regular treating physician for HTN, and use of emergency departments for HTN-related care. Health behavior risk factors include the following: alcohol use, illicit drug use, cigarette smoking, and dietary practices.9
Access to Health Care Resources
Access relates to factors including, but not limited to, cultural isolation, public awareness, individual and group attitudes, perception of resource availability, actual resources, socioeconomic status, educational level, and peer behavior.37-39 A difference between African Americans and whites is evident regarding the source of regular care.40 Collins and Winkleby3 found that African American women at risk for uncontrolled blood pressure had less frequent contact with a physician and were less likely to be taking antihypertensive medication. Hill et al9 found that only 49% of African American men had health insurance and 24% sought emergency care for HTN management. Shea et al28 examined correlates of nonadherence to HTN treatment in an inner-city minority African American population and concluded that altering the locus of care from emergency rooms to primary care physicians may improve adherence to HTN treatment in minority groups.
Given the harsh environment in which urban African Americans live,7 hypertensive African American women may abuse alcohol and illicit drugs. Examining only African American men, Kim et al19 found that alcohol and illicit drug use were negatively associated with HTN care behaviors. However, less attention has been paid to the examination of these relationships among African American women.
In contrast, other behaviors such as the lifestyle modifications of weight loss, reduced sodium intake, and increased physical activity are known to effectively lower blood pressure. In particular, the Dietary Approaches to Stop Hypertension diet has been found to be effective in reducing sodium and optimizing blood pressure in African Americans compared with whites.41-43 However, studies on the Dietary Approaches to Stop Hypertension diet were not sex specific, and dietary information affecting adherence to HTN treatment in African American women has not been reported.
The primary reinforcing factor in the model is social support. Social support, a strong independent factor in measuring adherence to treatment, is described as the comfort, assistance, and information perceived to be available through formal or informal contacts with individuals or groups. Instrumental social support refers to help on tangible problems, and emotional support refers to having someone to go to for personal matters, such as comforting gestures, that alleviate uncertainty, anxiety, hopelessness, and depression.44-46 Strogatz and James46 examined the association between social support and prevalence of HTN in a randomly selected sample of whites and African Americans (N = 2,030 adults) and found that African Americans were more likely to have low levels of both kinds of social support. Mitchell et al47 found that people who reported the existence of social support or social network exhibit reduced mortality relative to those who did not. Based on social learning theory, the family and others influence and create crucial behavior that affect healthcare, including adherence, with the potential of reward for appropriate behavior and the extinction of inappropriate behaviors. For instance, family eating behaviors are largely based on the foods selected by the one who purchases food.45,48
Evidence from the literature indicates that HTN in African American women is a major public health problem. Current advances in disease management indicate that HTN can be controlled. Several studies that include African American women have consistently identified the need for effective HTN management in this group. The intensive Hill-Levine model has shown effectiveness in controlling blood pressure in African American men. However, the relationships between adherence factors and blood pressure control remain unclear in African American women. Although the study of Levine et al10 used a nurse-supervised intervention process that included African American women, the results did not provide sex-specific information. Further study is needed to elucidate the barriers to blood pressure control in hypertensive African American women. Hughes and Hayman49 highlighted the need for nursing research to focus on sex-based differences in cardiovascular risk factors. Knowing the factors that influence treatment is critical to tailor the treatment for a high-risk group like hypertensive African American women. The Hill-Levine model has been applied effectively in controlling high blood pressure in African American men but has not been studied systematically in women. To provide a scientifically rigorous basis for culturally sensitive interventions targeted at adherence to antihypertensive treatment in African American women, there is a pressing need for studies that identify factors influencing hypertensive African American women's adherence to treatment and that describe the relationships of the identified predisposing, enabling, and reinforcing factors to antihypertensive treatment adherence in high-risk African American women.
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