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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population 5 Cardiovascular Disease Cardiovascular diseases are the leading cause of death and major contributors to medical utilization and disability (Havlik et al., 1987). In 1996, a total of 959,227 deaths occurred from cardiovascular diseases (CVD)1, including 476,227 deaths from coronary heart disease (CHD)2 and 159,942 from stroke (AHA, 1998). Table 5.1 displays mortality rates for heart disease by age, gender, and race or ethnicity from 1989 to 1991. It is evident from this table that heart disease afflicts both men and women, independent of race or ethnicity. Furthermore, there is a striking age-related rise in mortality from heart disease such that the vast majority of deaths due to heart disease occur in persons age 65 and older. The costs associated with CVD are enormous. According to data compiled by the American Heart Association (AHA, 1998), the estimated direct costs of health care for CVDs in 1999 will be $178.2 billion. An additional $108 billion in costs will occur as a result of indirect expenses. In view of the high prevalence and incidence of CVDs in the elderly, a substantial fraction of Medicare expenditures are related to these conditions. For instance, in 1995, Medicare spent $24.6 billion for hospital expenses 1 CVD refers to stroke and any disease pertaining to the heart and/or blood vessels. 2 CHD refers to conditions such as myocardial infarction and angina which result from an insufficient blood supply to the heart, typically from atherosclerotic changes in coronary arteries.
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population TABLE 5.1 Death Rate due to Heart Disease per 100,000 Population, 1989 to 1991 Men Women Age (years) White Black Hispanic White Black Hispanic 15–24 3 7 — 2 4 — 24–44 25 58 — 8 2 28 45–54 171 340 111 50 156 58 55–64 518 838 346 193 445 149 65–74 1,234 1,645 840 584 1,023 435 75–84 2,959 3,115 1,988 1,877 2,289 1,294 >85 7,515 6,343 4,861 6,550 5,767 4,488 SOURCE: Adapted from Srinath et al. (1995). Data for the age groups between 15 and 44 years were obtained from NCHS (1993). Data for the groups over age 45 were obtained from NCHS (1994). related to CVDs, an amount that corresponds to 33 percent of its hospitalization expenditures. Through well-accepted risk factors (i.e., dyslipidemia, hypertension), dietary factors have a prominent role in the genesis of athersclerotic CVDs (i.e., CHD, stroke, heart failure3 ). Although atherosclerosis is a chronic process beginning in youth, there is abundant evidence that therapies initiated in older-aged persons can prevent or delay clinical events. Furthermore, because of the high incidence of CVD events in older age, even relatively small improvements in risk factors (i.e., small reductions in blood pressure and low-density lipoprotein [LDL] cholesterol through diet), should be of substantial benefit to the general population. However, there is a lag period, likely 2 or more years, between the onset of therapy and a reduced risk of clinical events, such as CHD and stroke. The situation is quite different for heart failure, in which case adherence to dietary and medication therapies can lead to early benefits, such as reduced rate of hospitalization and reduced length of stay. The following sections discuss the role of diet as a means to improve cardiovascular risk factors (dyslipidemia and hypertension) and as a means to treat heart failure. DYSLIPIDEMIA Dyslipidemia is a powerful risk factor for atherosclerotic diseases, particularly CHD. The term dyslipidemia applies to a high blood level of 3 Heart failure refers to a clinical condition in which the heart becomes weakened or stiff and pumps blood inefficiently.
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population total cholesterol, as well as other abnormalities in blood lipid levels including an elevated LDL cholesterol level, a decreased high-density lipoprotein (HDL) cholesterol level, and an elevated triglyceride level. Each of these conditions increases the risk of atherosclerotic disease. Still, the primary focus of treatment has been on reducing total and LDL cholesterol (NCEP, 1994), each of which is amenable to nutrition therapy. Dyslipidemia is commonplace among the elderly. According to the Third National Health and Nutrition Examination Survey (NHANES III) (NCHS, 1997), approximately 28 percent of men and 43 percent of women, ages 65 to 74, have elevated total cholesterol defined as a total cholesterol greater than or equal to 240 mg/dL. A somewhat lower percentage of persons, ages 75 and older, have an elevated total cholesterol level (i.e., 19 percent of men and 39 percent of women). Such data underestimate the prevalence of dyslipidemia, which would include persons with an elevated LDL cholesterol level, a low HDL cholesterol level, or a high triglyceride level despite a total cholesterol level of less than 240 mg/dL. Furthermore, the actual prevalence is also underestimated by the number in these age groups under treatment for dyslipidemia. Current treatment guidelines advocate aggressive treatment of persons with less severe lipid abnormalities who have other risk factors for atherosclerotic disease or who have had prior CVD (NCEP, 1994). The relationship of blood levels of total and LDL cholesterol to subsequent CHD events has been documented in several major observational studies (e.g., Kahn et al., 1984; Martin et al., 1986; MRFIT, 1996; Shekelle et al., 1981) and in pooled analyses across 20 or more cohorts (Jacobs et al., 1992; Manolio et al., 1992). In general, the risk of CHD increases progressively as the blood levels of serum total and LDL cholesterol rise. The association of total mortality with total serum cholesterol is similar, except that total mortality may increase in the group of persons with the lowest levels of total cholesterol, perhaps as a result of the association of very low total cholesterol with serious noncardiovascular illnesses (Jacobs et al., 1992). Although it is generally recognized that LDL and total cholesterol are directly related to CHD risk, it is noteworthy that an increasing body of evidence has linked dyslipidemias to the occurrence of stroke (Ross et al., 1999). Also, a large body of evidence indicates that an elevated triglyceride level is at least a marker, if not an independent risk factor, for heart disease (Hokanson and Austin, 1996). In the elderly, the risk of CHD also increases with increasing blood levels of total and LDL cholesterol (Grundy et al., 1999; Manolio et al., 1992). Previous studies have questioned the importance of elevated cholesterol as a risk factor for CHD in the elderly. In part, such uncertainties resulted from the presentation of risk estimates (i.e., the ratio of CHD risk in high versus low cholesterol groups [risk ratio] conveys a different im-
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population pression than the absolute difference in CHD risk between groups with high and low cholesterol). Because CHD is commonplace in the elderly, even among persons with lower levels of serum cholesterol, the ratio of risks in high- versus low-cholesterol groups among the elderly is typically less than that observed in middle-aged persons. In fact, because of the high risk of CHD in the elderly, a reduction in blood cholesterol levels should prevent more CHD events than a comparable reduction in blood cholesterol in younger persons. Evidence that a Change in Risk Factors Affects Morbidity and Mortality Reduction of plasma cholesterol levels by dietary and/or pharmacological means has been shown to prevent CHD events both in persons with and without prior CHD. Effective interventions include several types of medications (bile acid sequestrants, niacin, and statin medications as prescribed by physicians) and dietary intervention. As a result of the inherent difficulties of conducting long-term dietary intervention trials, evidence tends to be stronger for drug therapies than for diet therapy (Muldoon et al., 1990). The health benefits from cholesterol reduction therapies occur without evidence of deleterious effects on noncardiovascular mortality. The magnitude of the reduction in CHD has been defined for people with initial serum cholesterol levels in the 250 to 300 mg/dL range. For each 1 percent reduction in the serum cholesterol level, a 2 percent reduction in the incidence of CHD is expected (Lipid Research Clinics Program, 1984). The benefits of cholesterol-reducing therapy extend to the elderly (Grundy et al., 1999). Both dietary therapies and pharmacologic therapies favorably affect lipid levels in the elderly (LaRosa et al., 1994) and can prevent CVD events. Of particular interest is the Los Angeles Veterans Administration domiciliary study that involved older men, average age 66 years, who were free of signs of definite CHD (Dayton et al., 1969). In this dietary intervention trial, moderate cholesterol reduction was achieved and sustained in the active intervention group by institutional feeding of a fat-modified diet, low in saturated fat and cholesterol and high in polyunsaturated fat. A significant 31 percent reduction in the incidence of severe atherosclerotic events (coronary, cerebral, peripheral) occurred over 8.5 years of follow-up. These findings lend strong support to the judgment that risk factor modification in the elderly can prevent CVD. In large-scale trials that enrolled persons without prior atherosclerotic cardiovascular disease (ASCVD) (Downs et al., 1998; Shepherd et al., 1995) and in other trials that enrolled persons with prior ASCVD (Sacks et
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population al., 1996; Scandinavian Simvastatin Survival Study Group, 1994), cholesterol lowering medication significantly reduced cardiovascular morbidity and mortality, and in several instances reduced total mortality. Additional aspects of these trials are noteworthy. First, in subgroup analyses restricted to older-aged enrollees, significant reductions in cardiovascular end points were documented. Second, in each trial, the effects of the medications were tested in individuals who were also being given nutrition therapy. Modifying Risk Factors Through Nutrition Therapy The mainstays of dietary counseling for dyslipidemia have been advice to reduce saturated fat and dietary cholesterol intake and to increase polyunsaturated fat intake (NCEP, 1994). Such approaches reflect observational studies that have linked these aspects of diet with lipid levels as well as clinical trials that tested the effects of modifying these nutritional factors on CHD. Although reductions in total fat have also been recommended, particularly for weight reduction or weight control, the emphasis of nutrition therapy for dyslipidemia has been a reduction in saturated fat. In general, diets high in unsaturated fat have been considered more successful than low-fat diets in lowering serum cholesterol levels and decreasing the risk of coronary artery disease (Sacks, 1998). Preliminary evidence suggests that other dietary strategies may also be effective. For instance, a diet rich in alpha-linolenic acid led to a significant reduction in the risk of subsequent coronary events in patients with previous CVD, even though cholesterol levels did not change (de Lorgeril et al., 1994, 1999). Also, Burr et al. (1989) demonstrated that advice to eat two fish meals weekly significantly decreased the risk of total mortality and coronary mortality in patients with previous myocardial infarction. To date, the impact of vitamin supplementation (i.e., either antioxidant vitamins or those given to reduce homocysteinemia) on CHD is uncertain. Evidence primarily from observational studies suggests that certain vitamin supplements, particularly folate and vitamin E, may decrease the risk of ASCVD in some population groups. For vitamin E, a few clinical trials have been completed. One trial demonstrated a reduction in ASCVD morbidity but not mortality from supplemental vitamin E among persons with preexisting CHD (Stephens et al., 1996). In another trial, a comparatively low dose of vitamin E had no benefit on ASCVD outcomes in approximately 20,000 Finnish male smokers (Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group, 1994). In a large secondary prevention trial, vitamin E had no significant benefit in preventing ASCVD (GISSI-Prevenzione Investigators, 1999). Overall, data are insuffi-
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population cient for recommendations pertaining to vitamin E as a means to prevent ASCVD. For folate supplements, evidence predominantly from retrospective observational studies (Boushey et al., 1995) indirectly suggests that an increased dietary intake of folate may prevent ASCVD; however, no clinical trials of supplemental folate have been completed. Hence, available evidence is insufficient to recommend either vitamin E or folate supplements as a means for preventing ASCVD. The Step I diet proposed by the National Cholesterol Education Program (NCEP, 1994) has been shown to decrease plasma total cholesterol by 7 to 9 percent compared with the average American diet (Stone et al., 1996). A Step II diet has been shown to decrease total cholesterol and LDL cholesterol by 10 to 20 percent (Stone et al., 1996). Short-term studies typically demonstrate greater effects than long-term studies, and feeding or metabolic studies achieve greater reductions than studies conducted in free-living persons (Kris-Etherton and Dietschy, 1997). Thirty-seven intervention studies published between 1981 and 1997 were analyzed by Yu-Poth et al. (1999). Some were sequential studies, but most were randomized, parallel-arm studies. The dietary interventions ranged from vegetarian diets providing less than 10 percent of energy as fat, less than 6 percent of energy as saturated fat, and less than 100 mg cholesterol to a Step I diet providing less than or equal to 30 percent of energy as fat, less than 10 percent of energy as saturated fat, and less than or equal to 300 mg cholesterol per day. Average reductions in LDL cholesterol were 12 percent with a Step I diet and 16 percent with a Step II diet. Changes in plasma total cholesterol, LDL cholesterol, and HDL cholesterol were significantly correlated with changes in dietary total fat and saturated fatty acids. Several studies utilized registered dietitians in their intervention programs. In a study of patients aged 22 to 79 with hypercholesterolemia (>5.20 mmol/L [>201 mg/dL]), assignment to a dietitian for nutrition therapy led to a mean reduction in serum cholesterol level of 9 percent. In a study by Katzel et al. (1995), a Step I isocaloric diet was sequentially compared to a Step I hypocaloric diet for 3 months in elderly men with silent myocardial ischemia. The sequential interventions decreased triglyceride levels by 44 percent, LDL cholesterol by 18 percent, and the LDL to HDL ratio by 19 percent. Reduction in total serum cholesterol levels correlated with increased time spent with a dietitian. A group of hypercholesterolemic patients (mean age 61) took part in an 8-week nutrition intervention program provided by registered dietitians before initiating treatment with a cholesterol-lowering medication (Sikand et al., 1998). The nutrition part of the intervention lowered total cholesterol by 13 percent (p > 0.001), LDL cholesterol by 15 percent (p >
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population 0.0001), triglyceride by 11 percent (p = 0.05), and HDL cholesterol by 4 percent (p = 0.05). After dietary counseling, 34 of 67 (51 percent) subjects were no longer candidates for drug therapy (per NCEP guidelines). The magnitude of LDL cholesterol reduction increased with greater time spent with the dietitian. A similar finding was also reported by McGehee and colleagues (1995), whose research documented that a minimum of two visits was required. HMG-CoA Reductase Inhibitors (Statins) β-Hydroxy-β-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) are medications that have potent effects on blood lipid levels. Through such effects (i.e., reductions in LDL cholesterol of 17–54 percent and total cholesterol of 6–21 percent), these medications have been shown to reduce total mortality by 24 percent, fatal heart attacks by 39 percent, nonfatal heart attacks by 31 percent, fatal stroke by 23 percent, and nonfatal stroke by 31 percent (Ross et al., 1999). The populations studied have included persons with prior heart attacks, persons without prior heart attacks but at high risk for CVD, and older-aged persons. The impressive impact of statin medications on lipid levels and clinical cardiovascular events has led some to reconsider the role of nutrition therapy in the management of persons with dyslipidemia. Still, there is a strong rationale to advocate nutrition therapy as initial therapy in persons not on statins and as adjunctive therapy in persons on medication. First, it is important to emphasize that the reductions in lipid levels and CVDs documented in trials of statin therapy were achieved in the context of concomitantly administered nutrition therapy. Second, through nutrition therapy, many persons can reduce their lipid levels to the point that they do not need or no longer require medication. A report from the National Cholesterol Education Adult Treatment Panel suggests that if all patients who are eligible for nutrition therapy experienced a 15 percent drop in LDL cholesterol, the number of patients who need drug therapy could be cut in half (Carleton et al., 1991). Third, as documented by Hunninghake et al. (1993) and others, the effects of medication and dietary therapies appear additive. Finally, dietary changes may provide additional benefits beyond that of lipid-lowering alone. Dyslipidemia: Summary and Recommendations Substantial evidence from observational studies and from randomized trials supports the use of nutrition therapy as a means for improving lipid profiles and thereby preventing or delaying CVD in the elderly. Furthermore, numerous professional organizations including the Ameri-
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population can Heart Association, the National Cholesterol Education Program of the National Heart, Lung, and Blood Institute, and the Second Joint Task Force of European and Other Societies on Coronary Prevention (Wood et al., 1998) advocate nutrition therapy as an integral part of routine medical therapy for persons with dyslipidemia. Recommendations for nutrition therapy extend to those individuals not on cholesterol-lowering therapy as well as persons on medications such as statins. Although the number and frequency of visits with a nutrition professional is uncertain, data suggest that at least two visits would be required. Additional research is needed to identify behavioral strategies that can accomplish and sustain long-term changes in dietary intake, the impact of different health care providers on lipid levels, and continued research on the optimal dietary pattern that reduces cardiovascular risk. Summary of Evidence—Nutrition Therapy for Dyslipidemia Consensus statements: Recommended as part of the standard of care in guidelines prepared by the American Heart Association (Krauss et al., 1996) and the National Heart, Lung and Blood Institute (LaRosa et al., 1990; NCEP, 1994) Observational studies: Strong evidence (e.g., Martin et al., 1986; Shekelle et al., 1981) Randomized trials: Strong evidence (e.g., Dayton et al., 1969; Downs et al., 1998; Lipid Research Clinic Program, 1984; Sacks et al., 1996; Shepherd et al., 1995) Systematic reviews: Several (e.g., Grundy et al., 1999; Jacobs et al., 1992; Ross et al., 1999; Stone et al., 1996; YuPoth et al., 1999) HYPERTENSION Elevated blood pressure is among the most common and important risk factors for ASCVD in the general population and among older-aged persons. According to NHANES III data, approximately 50 percent of the more than 30 million persons age 65 or older have hypertension (defined as a systolic blood pressure ≥140 mm Hg, a diastolic blood pressure ≥90 mm Hg, and/or the use of antihypertensive medication) (Burt et al., 1995). In certain groups, the prevalence of hypertension is almost ubiquitous; for example, nearly 80 percent of black women age 60 and older have hypertension (Burt et al., 1995). The evidence that elevated blood pressure is causally related to
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population ASCVD (both CHD and stroke) and to kidney disease is strong and consistent. Such data include the results of numerous longitudinal studies that assessed the occurrence of clinical ASCVD outcomes by blood pressure level. These studies were summarized in an analysis in which the relationship between blood pressure and both stroke and CHD was direct, progressive, and graded throughout the range of blood pressure (MacMahon et al., 1990). The relationship of end-stage renal disease to blood pressure is likewise direct and progressive (Klag et al., 1996). Although both systolic and diastolic blood pressure predict risk, systolic blood pressure tends to be a stronger predictor than diastolic blood pressure. More than 20 major clinical trials have assessed the impact of blood pressure-reducing pharmacologic therapy on clinical ASCVD events, including several studies conducted exclusively in older-aged persons (MRC Working Party, 1992; SHEP Cooperative Research Group, 1991; Staessen et al., 1997). The totality of evidence suggests that a typical diastolic blood pressure reduction of 5 to 6 mm Hg prevents approximately 40 percent of strokes and 15 percent of CHD events (Hebert et al., 1993). It is assumed that blood pressure reductions from nonpharmacologic interventions would likewise prevent ASCVD events, although direct evidence from clinical trials is unavailable, primarily because of the difficulty in conducting such trials. The contemporary approach to preventing blood pressure-related ASCVD includes nonpharmacologic blood pressure-reducing therapy (also termed lifestyle modification), as well as pharmacologic approaches. In individuals with hypertension, nonpharmacologic therapies can serve as initial therapy in Stage 1 hypertension4 before the addition of medication and as an adjunct to medication in persons already on drug therapy. In hypertensive patients with controlled blood pressure, nonpharmacologic therapies can facilitate medication stepdown or even withdrawal in certain individuals. In nonhypertensive individuals, nonpharmacologic interventions have the potential to prevent the onset of hypertension and, more broadly, to reduce blood pressure and thereby lower the risk of ASCVD in the general population (National High Blood Pressure Education Program Working Group, 1993). The Sixth Report of the Joint National Committee on the Detection, Evaluation and Treatment of High Blood Pressure (JNC VI, 1997) concluded that several dietary approaches effectively lower blood pressure (i.e., reduced sodium intake, weight loss, reduced alcohol consumption, increased potassium intake, and adoption of an overall healthy diet, such 4 Stage 1 hypertension refers to either a systolic blood pressure of 140 to 159 mm Hg or a diastolic blood pressure of 90 to 99 mm Hg.
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population as the Dietary Approaches to Stop Hypertension Trial [DASH] diet). The evidence supporting these recommendations comes from observational studies as well as controlled clinical trials. Reduced Sodium Intake The preponderance of available evidence indicates that a high intake of salt (sodium chloride) adversely affects blood pressure. Such data include results from observational studies of diet and blood pressure (Intersalt Cooperative Research Group, 1988; Khaw and Barrett-Connor, 1990) and clinical trials of reduced salt intake. In three meta-analyses of randomized trials (Cutler et al., 1997; Graudal et al., 1998; Midgley et al., 1996), a reduced sodium intake lowered both systolic and diastolic blood pressure in hypertensive patients (range of pooled effects, 3.9–5.9 mm Hg for systolic blood pressure and 1.9–3.8 mm Hg for diastolic blood pressure); lesser reductions occurred in normotensive individuals. Many older-aged persons and African-Americans of all age groups appear particularly sensitive to the effects of salt on blood pressure. Recent trials show that behavior change interventions can reduce intake by approximately 30 to 50 mmol per day in the elderly (Whelton et al., 1998) and in other population groups (Neaton et al., 1993; TOHP Collaborative Research Group, 1992, 1997). Weight Loss A persuasive and consistent body of evidence from both observational and experimental studies indicates that weight is positively (directly) associated with blood pressure and hypertension (Stamler, 1991). The importance of this relationship is reinforced by the high and increasing prevalence of overweight in the United States (Kuczmarski et al., 1994). According to NHANES III data, the combined prevalence of overweight and obesity (a body mass index of >25 kg/m2) is 59 percent in men and 51 percent in women (NIH, 1998). All but one of the 16 clinical trials that examined the influence of weight loss on blood pressure in hypertensive individuals have documented a substantial and significant reduction in blood pressure from weight loss interventions (NIH, 1998). Reductions in blood pressure occur before (and without) attainment of desirable body weight. In one study that aggregated results across 11 weight loss trials, the average systolic and diastolic blood pressure reduction per kilogram of weight loss was 1.6/1.1 mm Hg (Staessen et al., 1989). Recent lifestyle intervention trials have uniformly achieved short-term weight loss. In several instances (Neaton et al., 1993; Whelton et al., 1998), substantial weight loss has also been sustained over the long term (3 or more years).
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population Reduced Alcohol Intake The relationship between high alcohol intake (typically three or more drinks per day) and elevated blood pressure has been reported in a large number of observational studies (Klatsky et al., 1977; MacMahon, 1987). A few trials have also demonstrated that reductions in alcohol intake among heavy drinkers can lower blood pressure in normotensive and hypertensive men (Puddey et al., 1985, 1987). In the Prevention and Treatment of Hypertension Study, a reduction in alcohol intake among non-dependent moderate to heavy drinkers also reduced blood pressure to a small, nonsignificant, extent (Cushman et al., 1998). Increased Potassium Intake In contrast to the direct relationship of sodium intake with blood pressure, the relationship between potassium intake and blood pressure is inverse (i.e., high levels of potassium are associated with low blood pressure). Whereas observational data have been reasonably consistent, the data from clinical trials have been less consistent and persuasive. However, a recent meta-analysis has documented a significant impact of potassium supplements on blood pressure (Whelton et al., 1997). On average, supplementation of the diet with a typical dose of 60 to 120 mmol of potassium per day reduced systolic and diastolic blood pressure, respectively, by 4.4 and 2.5 mm Hg in hypertensives and by 1.8 and 1.0 mm Hg in normotensives. This analysis also documented greater blood pressure reduction from potassium supplementation at higher levels of salt intake. Because a high intake of potassium can easily be achieved through diet and because potassium derived from foods also comes with a variety of other nutrients, the preferred strategy for increasing potassium intake is via foods rather than supplements. Healthy Dietary Pattern Certain dietary patterns have been associated with low blood pressure. For instance, in observational studies, vegetarian diets have been associated with lower blood pressure even after controlling for other factors known to affect blood pressure (Sacks et al., 1974). In clinical trials, vegetarian diets also reduced blood pressure (Margetts et al., 1986; Rouse et al., 1983). Such findings spawned efforts to identify the nutrients responsible for blood pressure reduction, especially since vegetarian diets are not widely followed in the general population. The nutrients responsible for the blood pressure-lowering effects of these diets have remained elusive. Attention has focused on macronutri-
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population Observational studies: Strong evidence (e.g., Intersalt Cooperative Research Group, 1988; Khaw and Barrett-Connor, 1990) Randomized trials: Several consistent trials in the elderly (Applegate et al., 1992; Cappuccio et al., 1997; Whelton et al., 1998) as well as numerous trials in other populations Systematic reviews: Several (Cutler et al., 1997; Graudal et al., 1998; Midgley et al., 1996; NIH, 1998) HEART FAILURE Heart failure is a major public health problem. According to the National Heart, Lung, and Blood Institute, more than 2 million Americans have heart failure, about 400,000 new cases occur annually, and about 200,000 people die each year of this disease. Heart failure is the most frequent cause of hospitalization among Medicare beneficiaries, accounting for more than 1 million hospitalizations per year. Heart failure is now considered the most costly cardiovascular illness in the United States (Rich and Nease, 1999). Heart failure is a clinical syndrome resulting from several conditions that damage the heart (e.g., uncontrolled hypertension; myocardial infarction; viral, alcohol-related, or idiopathic cardiomyopathies). In these instances, the heart becomes weakened or stiff and pumps blood ineffectively. Although heart failure can occur at any age, the vast majority of heart failure patients are elderly. The symptoms and signs of heart failure reflect volume or fluid overload (fluid in the lungs, abdomen, or legs [edema]) and/or inadequate perfusion of tissues, resulting in fatigue and poor exercise tolerance. Clinically, it is characterized by intermittent, acute exacerbations of symptoms. Between these acute episodes, patients are either in a state of well-compensated heart failure, which is virtually asymptomatic, or in a clinical state characterized by chronic symptoms of leg swelling (edema), fatigue, and/or shortness of breath. During the acute exacerbations, severe shortness of breath from accumulation of fluid in the lungs and/or excessive edema are the typical symptoms that prompt hospitalization. In addition to pharmacologic therapy for heart failure, nonpharmacologic therapies are commonly recommended as standards of care. The goals of therapy, both pharmacologic and nonpharmacologic, are to control symptoms, improve the quality of life, prolong survival, and prevent acute exacerbations that prompt hospitalization. Previously, digoxin and diuretics had been the mainstay of drug therapy. Recently, medical therapy has improved considerably. Specifically, angiotensin-converting
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population enzyme inhibitors and beta-blockers have been shown to increase survival and improve quality of life (Garg and Yusuf, 1995; Rich and Nease, 1999). The primary, diet-related nonpharmacologic therapy is sodium restriction, which should reduce the extent of fluid overload and potentially lower the dose of diuretic therapy. Water restriction is also recommended for patients with severe heart failure, who are at risk of hyponatremia. Interestingly, no trial has specifically tested the effects of dietary recommendations alone in the management of heart failure. The absence of such data does not reflect uncertainty over this aspect of heart failure treatment. Rather, sodium restriction has been and remains a widely accepted component of standard medical care for heart failure patients. Presently, joint guidelines from the American College of Cardiology and the American Heart Association (Packer and Cohn, 1999) and guidelines from the Agency for Healthcare Research and Quality (formerly the Agency for Health Care Policy and Research (AHCPR, 1994) recommend diet therapy as a component of the standard management of patients with heart failure. The factors leading to exacerbations of heart failure include nonadherence to medication or diet, inadequate therapy, social or environmental issues, abnormal heart rhythms, and intercurrent noncardiac conditions. In one case series from an urban medical center, the most common factor associated with hospital admissions for heart failure was noncompliance with the medical regimen (diet and/or drugs), and was present in 64 percent of patients admitted with heart failure (Ghali et al., 1988). Other common factors were cardiac arrhythmias (29 percent), social or environmental issues (26 percent), inadequate therapy (17 percent), and pulmonary infections (12 percent) (many persons had several problems simultaneously). In view of the diversity of these precipitating factors, subsequent studies have evaluated the effects of multidisciplinary programs designed to improve several aspects of care, rather than unidimensional programs (e.g., nutrition therapy alone). In a comprehensive review of the medical literature on nonpharmacologic treatments for heart failure, Dracup et al. (1994) concluded that counseling and education can improve medical outcomes and decrease hospitalizations. At the time of that publication, only one study had demonstrated reduced numbers of hospitalizations from such interventions. Specifically, in a nonrandomized trial (Rosenberg, 1971), a group-based, behavioral intervention program designed to improve compliance with diet and medications reduced hospital admissions compared to the previous year (46 versus 12 percent) and compared to patients at another hospital (31 versus 17 percent). Subsequent studies that used stronger research methods have corroborated the above findings. As part of a larger trial examining the ef-
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population fects of a single, postdischarge home intervention visit across a broad population of hospitalized patients in Australia, Stewart et al. (1999) reported the effects of this visit on 97 heart failure patients. The post-discharge visit included measures to optimize medication management, identify early clinical deterioration, and intensify medical follow-up and caregiver vigilance. In comparison to the control group, the group that received the postdischarge visit (by a nurse and pharmacist) had fewer unplanned readmissions (64 versus 125, p = 0.02) and outpatient deaths (2 versus 9, p = 0.02) over 18 months. In another randomized controlled trial, Rich et al. (1995) tested the effects of an intensive intervention (with both inpatient and home care components) in older-aged patients (aged 70+) who were hospitalized for heart failure and were at risk for readmission. The intervention team included a cardiovascular research nurse, registered dietitian, social worker, and cardiologist. During the inpatient phase of the intervention, the dietitian completed a dietary assessment and provided individualized instruction on sodium reduction that subsequently was reinforced by the study nurse. Over a follow-up period of 90 days, the intensive intervention compared to control led to fewer patients who were readmitted (29 versus 42 percent of patients, p = 0.03), fewer days of hospitalization (556 versus 865, p = 0.04), and fewer readmissions for heart failure (24 versus 54, p = 0.04). In a randomized, controlled clinical trial conducted in Sweden, Cline et al. (1998) evaluated the effects of a nurse-directed intervention that provided patient education and promoted adherence and self-monitoring to patients hospitalized for heart failure. The nurse provided the counseling during the hospitalization and in an outpatient clinic. Compared to control participants at 1 year, patients assigned to the intervention group had a longer mean time to readmission (141 versus 106 days, p < 0.05), trends toward fewer hospitalizations (0.7 versus 1.1, p = 0.08) and readmissions per patient (39 versus 54 percent, p = 0.08), a shorter length of hospital stay (4.2 versus 8.2 days, p = 0.07), and lower mean annual health costs (U.S. $2,294 versus $3,594 per patient, p = 0.07). One-year mortality rates and quality of life did not differ between the two groups. Kostis et al. (1994) tested the effects of a multidimensional, intensive nonpharmacologic approach (a 12-week outpatient program of diet, exercise, and cognitive-behavioral therapy, presented in a group format) in comparison to two other treatments (digoxin alone and placebo). The dietary component of the program, which focused on reducing salt intake and reducing weight (among overweight participants), was conducted by a dietitian who led weekly meetings. The study population consisted of 20 outpatients (mean age 65 years) with moderate heart failure. In the digoxin group, the ejection fraction improved (as measured by echocar-
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population diography) but without corresponding changes in exercise tolerance or quality-of-life. In contrast, the nonpharmacologic approach improved exercise tolerance, improved mood, and reduced weight. In response to such studies, multidisciplinary “heart failure teams” have been established at many medical centers as a means to reduce morbidity and mortality from heart failure, as well as prevent hospitalizations and their attendant costs. Typically, the team is overseen by a cardiologist and directed by a nurse experienced in the management of patients with heart failure. Dietitians and exercise counselors are often members of such teams. The structure, content and setting of the programs also vary. Component activities include education about heart failure and its treatment; medication adjustment; efforts to improve adherence to diet and medication and to increase physical activity; discharge planning in the setting of hospitalizations; telephone follow-up; and self-monitoring. In a recent review by Rich and Nease (1999), such multidisciplinary programs are cost-effective and potentially cost saving. Some heart failure programs have reported their experience. At the University of Nebraska, a multidisciplinary team has reduced hospital days by 42 percent, hospital admissions by 30 percent, and length of stay by 17 percent (Chapman and Torpy, 1997). Pezzella et al. (1997) reported on an ambulatory program designed to reduce readmissions in high-risk heart failure patients. Each patient received comprehensive education provided by a primary care nurse in collaboration with a registered dietitian. The nutrition component consisted of a 45–60 minute group session in which the nutrition professional used participatory, problem-solving strategies to implement dietary recommendations, and individual counseling sessions as needed on referral by the primary care nurse. Preliminary data indicate a 1-day reduction in length of stay and a decrease of 60-day readmission rate by 1.1 percent (using historical utilization data). Heart Failure: Summary and Recommendations Available evidence from several small clinical trials and a few observational studies supports the use of nutrition therapy in the context of multidisciplinary programs. Such programs can prevent readmissions for heart failure, reduce subsequent length of stay, and improve functional status and quality-of-life. The programs often include both inpatient predischarge counseling and outpatient components that may even be home based. Evidence is unavailable to separate the effects of nutrition therapy from other aspects of these programs and to compare the effectiveness of different types of counselors (dietitians versus nurses). In view of the high costs of managing heart failure, particularly admissions for heart failure exacerbations, and the rapid response to therapies, there is a real
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population potential for cost savings from multidisciplinary heart failure programs that include nutrition therapy. The high morbidity, mortality, and costs associated with heart failure and the paucity of data on the effects of nutritional therapies in this condition provide a strong rationale for additional research. Summary of Evidence—Nutrition Therapy for Heart Failure Consensus statements: Recommended as part of standard of care in guidelines prepared by the American College of Cardiology (Packer and Cohn, 1999), American Heart Association (AHA, 1999), and by the Agency for Health Care Policy and Research (AHCPR, 1994) Observational studies: Consistent evidence from diverse types of studies (Chapman and Torpy, 1997; Ghali et al., 1988; Rosenberg, 1971) Randomized trials: Consistent evidence from a few small clinical trials (Kostis et al., 1994; Rich et al., 1995; Stewart et al., 1999) that tested the effects of programs that included nutrition therapy Systematic review: Dracup et al. (1994); Rich and Nease (1999) RESEARCH RECOMMENDATIONS Available evidence strongly supports the efficacy of nutrition therapy as a means to improve lipid profiles, reduce blood pressure and, in the context of multidisciplinary programs, treat heart failure. Still, there are numerous unresolved issues that include the following: What is the optimal diet that reduces cardiovascular risk? For instance, although there is a broad consensus that the diet should be low in saturated fat, it is unclear what type of nutrient (protein, carbohydrate, or unsaturated fat) should replace saturated fat as the source of calories. Does supplementation of diet with specific nutrients have a cardioprotective role? For instance, preliminary studies suggest that certain nutrients (e.g., folate or other B vitamins) may reduce the risk of CVD. However, clinical trials are needed to confirm the efficacy and safety of diet supplementation with any nutrient. What are the optimal public health strategies that accomplish favorable dietary changes? In view of the high prevalence of hypertension and dyslipidemia, efficient and effective strategies need to be developed and tested in a rigorous fashion.
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The Role of Nutrition in Maintaining Health in the Nation’s Elderly: Evaluating Coverage of Nutrition Services for the Medicare Population What is the optimal intervention strategy for use in the clinic setting? Corollary issues are to determine the number of provider contacts required to accomplish dietary change, the impact of different types of nutrition providers, and the impact of individual-based versus group-based interventions. What dietary changes other than sodium reduction (e.g., weight loss, DASH diet) favorably affect the course of congestive heart failure? REFERENCES AHA (American Heart Association). 1999. 1999 Heart and Stroke Statistical Update. Dallas, Tex.: American Heart Association. AHCPR (Agency for Health Care Quality and Research). 1994. Heart Failure: Management of Patients With Left-Ventricular Systolic Dysfunction. Quick Reference Guide for Clinicians, No. 11. Rockville, Md.: AHCPR. Allender PS, Cutler JA, Follmann D, Cappuccio FP, Pryer J, Elliott P. 1996. Dietary calcium and blood pressure: A meta-analysis of randomized clinical trials. Ann Intern Med 124:825–831. Alpha-Tocopheral, Beta Carotene Cancer Prevention Study Group. 1994. The effect of vitamin E and beta carotene on the incidence of lung cancer and other cancers in male smokers. N Eng J Med 330:1029–1035. Appel LJ, Moore TJ, Obarzanek E, Vollmer WM, Svetkey LP, Sacks FM, Bray GA, Vogt TM, Cutler JA, Windhauser MM, Lin P-H, Karanja N. 1997. A clinical trial of the effects of dietary patterns on blood pressure. N Engl J Med 336:1117–1124. Applegate WB, Miller ST, Elam JT, Cushman WC, El Derwi D, Brewer A, Graney MJ. 1992. Nonpharmacologic intervention to reduce blood pressure in older patients with mild hypertension. Arch Intern Med 152:1162–1166. Boushey CJ, Beresford SAA, Omenn GS, Motulsky AG. 1995. A quantitative assessment of plasma homocysteine as a risk factor for vascular disease. Probable benefits of increasing folic acid intakes. J Am Med Assoc 274:1049–1057. Burr ML, Fehily AM, Gilbert JF, Rogers S, Holliday RM, Sweetnam PM, Elwood PC, Dead-man NM. 1989. Effects of changes in fat, fish, and fibre intakes on death and myocardial reinfarction: Diet and Reinfarction Trial. Lancet 2:757–761. Burt VL, Whelton P, Roccella EJ, Brown C, Cutler JA, Higgins M, Horan MJ, Labarthe D. 1995. Prevalence of hypertension in the U.S. adult population. Results from the Third National Health and Nutrition Examination Survey, 1988–1991. Hypertension 25:305–313. Cappuccio FP, Elliott P, Allender PS, Pryer J, Follman DA, Cutler JA. 1995. Epidemiologic association between dietary calcium intake and blood pressure: A meta-analysis of published data. Am J Epidemiol 142:935–945. Cappuccio FP, Markandu ND, Carney C, Sagnella GA, MacGregor GA. 1997. Double-blind randomised trial of modest salt restriction in older people. Lancet 350:850–854. Carleton RA, Dwyer J, Finberg L, Flora J, Goodman, DS, Grundy SM, Havas S, Hunter GT, Kritchevsky D, Lauer RM, Luepker RV, Ramirez AG, Van Horn L, Stason WB, Stokes J III. 1991. Report of the Expert Panel on Population Strategies for Blood Cholesterol Reduction. A statement from the National Cholesterol Education Program, National Heart, Lung, and Blood Institute, National Institutes of Health. Circulation 83:2154–2232.
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Representative terms from entire chapter: