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Hypertension - Epidemiology HYPERTENSION IN RACIAL AND ETHNIC MINORITIES The United States is a diverse nation composed of individuals from many cultures. The 1990 census reported that the U.S. population was 0.8 percent American Indians, Aleuts, and Inuits; 2.9 percent Asians and Pacific Islanders; 9.0 percent persons of Hispanic origin; 12.1 percent African Americans; and 80.3 percent white.146 (These self-reported categories are not mutually exclusive; thus, the total is greater than 100 percent.) In the past decade, the country has experienced a marked increase in minority populations and the number of immigrants. This trend is expected to continue. As immigrant populations acculturate, their risk for cardiovascular disease changes. The prevalence of hypertension differs among racial and ethnic groups compared with the general population.1 For example, American Indians have the same prevalence as, or a higher prevalence than, the general population; among Hispanics, blood pressure is generally the same as or lower than that of non-Hispanic whites, despite a high prevalence of obesity and type 2 diabetes mellitus. It also appears that South Asians are more responsive to various antihypertensive medications than whites. Evidence shows that hypertension awareness, treatment, and control in some groups, especially those with generally lower socioeconomic status, require more focused hypertension education and intervention programs.The prevalence of hypertension in African Americans is among the highest in the world. Compared with whites, hypertension develops earlier in life and average blood pressures are much higher in African Americans. African Americans have higher rates of stage 3 hypertension than whites, causing a greater burden of hypertension complications. This earlier onset, higher prevalence, and greater rate of stage 3 hypertension in African Americans is accompanied by an 80-percent higher stroke mortality rate, a 50-percent higher heart disease mortality rate, and a 320-percent greater rate of hypertension-related end-stage renal disease than seen in the general population. Available evidence indicates that, compared with whites, African Americans receiving adequate treatment will achieve similar overall declines in blood pressure and may experience a lower incidence of cardiovascular disease. However, African Americans often do not receive treatment until blood pressure has been elevated a long time and target organ damage is present. This also may account for the higher incidence of hypertension-related morbidity and mortality in the African American population, including end-stage renal disease. Because of the high prevalence of cardiovascular risk factors in African Americans—such as obesity, cigarette smoking, and type 2 diabetes—as well as increased responsiveness to reduced salt intake, lifestyle modifications are particularly important. In African Americans, as well as in whites, diuretics have been proven in controlled trials to reduce hypertensive morbidity and mortality; thus, diuretics should be the agent of first choice in the absence of conditions that prohibit their use. Calcium antagonists and alpha-beta-blockers are also effective in lowering blood pressure. Monotherapy with beta-blockers or ACE inhibitors is less effective, but the addition of diuretics markedly improves response. However, these agents are indicated regardless of ethnicity when patients have other specific indications (e.g., beta-blockers for angina or post-myocardial infarction, ACE inhibitors for diabetic nephropathy or left ventricular systolic dysfunction). Because of their greater prevalence of stage 3 hypertension, many African American patients require multidrug therapy. Every effort should be made to achieve a goal blood pressure of below 140/90 mm Hg. In patients with renal insufficiency, recent data suggest that reducing blood pressure to an even lower level may be beneficial. HYPERTENSION IN CHILDREN AND ADOLESCENTS The fifth Korotkoff sound is now used to define DBP for all ages. Definitions of hypertension take into account age and height by sex. Blood pressure at the 95th percentile or greater is considered elevated (table 14). Clinicians should be alert to the possibility of identifiable causes of hypertension in younger children. Lifestyle interventions should be recommended, with pharmacologic therapy instituted for higher levels of blood pressure or if there is insufficient response to lifestyle modifications. Although the recommendations for choice of drugs are similar in children and adults, dosages of antihypertensive medication should be smaller and adjusted very carefully for children. ACE inhibitors and angiotensin II receptor blockers should not be used in pregnant or sexually active girls. Uncomplicated elevated blood pressure alone should not be a reason to restrict asymptomatic children from participating in physical activities, particularly because exercise may lower blood pressure and prevent hypertension. Use of anabolic steroid hormones for the purpose of body-building should be strongly discouraged. Efforts should be made to discover other risk factors (e.g., smoking) in children, and interventions should be made if they are present. Detailed recommendations regarding hypertension in children and adolescents can be found in the 1996 report by the NHBPEP Working Group on Hypertension Control in Children and Adolescents.
HYPERTENSION IN WOMEN/ Large, long-term clinical trials of antihypertensive treatment have included both men and women and have not demonstrated clinically significant sex differences in blood pressure response and outcomes. Recent trials of older persons support a similar approach to hypertension management in men and women.
Hypertension Associated With Oral Contraceptives Women taking oral contraceptives experience a small but detectable increase in both SBP and DBP, usually within the normal range. Hypertension has been reported to be two to three times more common in women taking oral contraceptives, especially in obese and older women, than in those not taking oral contraceptives. 161Pr Women age 35 and older who smoke cigarettes should be strongly counseled to quit; if they continue to smoke, they should be discouraged from using oral contraceptives.If hypertension develops in women taking oral contraceptives, it is advisable to stop their use. Blood pressure will normalize in most cases within a few months. If high blood pressure persists, if the risks for pregnancy are considered to be greater than the risks for hypertension, and if other contraceptive methods are not suitable, then oral contraceptives may have to be continued and therapy for hypertension begun. A prudent approach to the use of oral contraceptives is to prescribe no more than a 6-month supply at a time in order to measure blood pressure on a semiannual basis.
Hypertension in Pregnancy Chronic hypertension is high blood pressure that is present and observable before pregnancy or that is diagnosed before the 20th week of gestation. The goal of treatment for women with chronic hypertension in pregnancy is to minimize the short-term risks of elevated blood pressure to the mother while avoiding therapy that compromises the well-being of the fetus. If taken before pregnancy, diuretics and most other antihypertensive drugs, except ACE inhibitors and angiotensin II receptor blockers, may be continued. Methyldopa has been evaluated most extensively and is therefore recommended for women whose hypertension is first diagnosed during pregnancy. Beta-blockers compare favorably with methyldopa with respect to efficacy and are considered safe in the latter part of pregnancy; however, their use in early pregnancy may be associated with growth retardation of the fetus (table 15). ACE inhibitors and angiotensin II receptor blockers should be avoided because serious neonatal problems, including renal failure and death, have been reported when mothers have taken these agents during the last two trimesters of pregnancy.Preeclampsia. Preeclampsia, a pregnancy specific condition, is increased blood pressure accompanied by proteinuria, edema, or both and at times by abnormalities of coagulation and renal and liver function that may progress rapidly to a convulsive phase, eclampsia. Preeclampsia occurs primarily during first pregnancies and after the 20th week of gestation. It may be superimposed on preexisting chronic hypertension. Large trials have not confirmed the benefit of prophylactic low-dose aspirin or supplemental calcium to prevent preeclampsia. A detailed summary of hypertension in pregnancy was published in a report by the NHBPEP Working Group on High Blood Pressure in Pregnancy.
Estimates based on the 1988-91 National Health and Nutrition Examination Survey (NHANES III) indicate that approximately 50 million, or one in every four, adults in the United States have high blood pressure (BP) on the basis of observations at a single evaluation (antihypertensive drug therapy, systolic blood pressure 140 mmHg, or diastolic blood pressure 90 mmHg) (data calculated by Centers for Disease Control, National Center for Health Statistics, Hyattsville, Maryland, for the National High Blood Pressure Education Program Coordinating Committee). The number meeting the recommended Joint National Committee criteria for diagnosis of hypertension (antihypertensive drug therapy or high BP measurements confirmed at two or more subsequent visits) is smaller, probably in the range of 30-40 million persons. No matter how conservative the criteria for recognition of hypertension, however, high BP is among the most common of the risk factors for cardiovascular-renal disease. The prevalence of high BP rises progressively with increasing age (table 1). It is higher in blacks than in whites (1). In youth and early middle age, men have a higher prevalence of high BP than women, but the reverse is true in later life. High BP is associated with an increased risk of developing coronary heart disease, stroke, congestive heart failure, renal insufficiency, and peripheral vascular disease (3-5). This risk has been noted in both sexes and throughout the entire adult age range. Compared to normotensives, the absolute excess in risk for hypertensives becomes progressively more important with increasing age (6,7). For many years, interest focused on the risk associated with high diastolic blood pressure (DBP). Increasingly, however, the importance of elevations in systolic blood pressure (SBP) has also been recognized and emphasized. The risks of morbidity and mortality from cardiovascular diseases increase in a curvilinear fashion with progressively higher levels of systolic and diastolic BP. This pattern is illustrated in figure 1, which displays the rate of BP- associated cardiovascular disease mortality during 12.5 years of followup of approximately 350,000 Multiple Risk Factor Intervention Trial (MRFIT) screenees with no history of myocardial infarction at baseline. Clearly, the risk of cardiovascular disease mortality increases progressively with incremental increases in BP from the optimal level of < 120 mmHg systolic and < 80 mmHg diastolic to the highest levels of SBP and DBP with little evidence of a threshold in risk. |
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