NUTRITION SCREENING AND ASSESSMENT
Older persons suffer a burden of malnutrition that spans the spectrum from under- to overnutrition. Nutritional problems accompany many of the chronic disease processes that afflict older persons. Moreover, age-related changes in physiology, metabolism, and function may alter the older person’s nutritional requirements. Better understanding among clinicians of the aging process and of nutritional screening, assessment, and interventions could potentially improve the health and independence of older persons.
Aging is associated with notable changes in body composition: bone mass, lean mass, and water content all decrease, while fat mass increases. The increase in total body fat is commonly accompanied by greater intra-abdominal fat stores. The consequence of these changes in body composition is that well-standardized nutrient requirements for younger or middle-aged adults cannot be generalized to older persons. The aging process also affects organ functions, although the degree of change observed is highly variable among individuals. Decline in organ functions may affect nutritional assessment and intervention.
Reduced basal metabolic rate in older persons reflects loss of muscle mass. The basal metabolic rate is the principal determinant of total energy expenditure; energy expenditure in relation to physical activity is the most variable component. The Harris-Benedict equations may be used to predict basal energy expenditure. A simple method for estimating the total daily energy needs of the older patient is based on body weight alone (Table 24.1). In any determination of energy needs for older persons, care must be taken to avoid overfeeding while still meeting basal requirements.
Modified food guide pyramids for older persons based upon the U.S. Department of Agriculture food guide pyramid have been released (Russell RM, Rasmussen H, Lichtenstein AH. Modified food guide pyramid for people over seventy years of age. J Nutr. 1999;129:751–753. See also http://nutrition.tufts.edu/consumer/pyramid.html). The food selections are more relevant to the target audience, and appropriate intakes of water, fiber, and supplements of calcium, vitamin D, and vitamin B12 are highlighted. The new USDA food pyramid (http://www.mypyramid.gov) released in 2005 may offer opportunity to further tailor recommendations for older persons.
The Food and Nutrition Board of the Institute of Medicine has released macronutrient guidelines that recommend a prudent diet, with 20% to 35% calories as fat and reduced intakes of cholesterol, saturated fat, and trans-fatty acids. Carbohydrates should constitute 45% to 65% of total calories; complex carbohydrates are the preferred fiber source. More specifically, the recommended fiber intake for those aged 60 years and over is 30 g for men and 21 g for women. Protein intake is recommended at 0.8 g per kg of body weight per day at approximately 10% to 35% of total calories. With stress or injury, protein requirements are typically estimated at 1.5 g per kg of body weight per day, but underlying renal or hepatic insufficiency may warrant protein restriction (Table 24.1).
Revisions of the Dietary Reference Intakes include recommended dietary allowances (RDAs) with more specific guidelines for older persons; those for the group aged 71 years and older are shown in Table 24.2.
Dehydration is the most common fluid or electrolyte disturbance in older persons. Normal aging is associated with a decreased perception of thirst, impaired response to serum osmolarity, and reduced ability to concentrate urine following fluid deprivation. A decline in fluid intake can also result from disease states that cause a reduction in mental or physical ability to recognize or express thirst, or that result in decreased access to water. In general, fluid needs of older persons can be met with 30 mL per kg of body weight per day or 1 mL per kcal ingested. Fluid needs may be altered during episodes of fever or infection, as well as with diuretic or laxative therapy. Common signs of dehydration are decreased urine output, elevated body temperature, constipation, mucosal dryness, skin turgor changes, and confusion. Altered fluid status (overhydration or underhydration) may affect anthropometric and biochemical measures, resulting in inaccurate assessments.
Anthropometric measurements are a mainstay of nutritional assessment of older persons. An unintended weight loss of 10 pounds in the preceding 6 months is a useful indicator of morbidity. This degree of weight loss is predictive of functional limitations, health care charges, and need for hospitalization. The Minimum Data Set (MDS) used by Medicare-certified nursing homes defines weight loss as 5% or more in the past month or 10% or more in the past 6 months. Body mass index (BMI)—weight in kilograms / (height in meters)2—has received increasing attention. National Institutes of Health guidelines regarding body size classification have been released (Table 24.3). BMI is a useful measure of body size and indirect measure of body fatness that does not require the use of a reference table of ideal weights. The risk threshold for low BMI is set at 18.5. Other anthropometric tools include skin-fold and circumference measurements, but these have had limited practical application because of the difficulty of training personnel to achieve acceptable reliability.
Generally, inadequate nutritional intake has been defined as average or usual intake of servings of food groups, nutrients, or energy below a threshold level of the RDA. The limited reliability of accurately assessing dietary intake measures is well known, so thresholds of 25% to 50% below the RDA have generally been selected. A study found reduced energy intake (less than 50% of calculated maintenance energy requirements) in 21% of a sample of hospitalized older persons. This subset of patients had higher rates of in-hospital mortality and 90-day mortality than did those above the threshold of energy intake. The MDS uses a different measure: intake of less than 75% of food provided is the threshold to trigger nutrition assessment in nursing homes. Surveys of nutritional status conducted among chronically institutionalized older persons suggest that 5% to 18% of nursing-home residents have energy intakes below their recommended average energy expenditure.
Energy intakes of men and women aged 65 to 98 years have been estimated in a nationwide food consumption survey. Investigators report that 37% to 40% of the men and women studied had energy intakes lower than two thirds of the RDA, and many reported skipping at least one meal each day. Estimated intakes by consumption surveys, however, may be unreliable because some studies suggest that older persons under-report energy intakes by 20% to 30%.
Food security issues are prevalent contributors to inadequate nutritional intakes among older persons. It is important to ascertain whether limitations in resources, transportation, or functionality may limit access to food or ability to prepare food.
Serum albumin has been recognized as a risk indicator for morbidity and mortality. Hypoalbuminemia lacks specificity and sensitivity as an indicator of malnutrition; however, it may be associated with injury, disease, or inflammatory conditions. As a negative acute phase reactant, it is subject to cytokine-mediated decline in synthesis and to increased degradation and transcapillary leakage. It is thought that albumin synthesis does not decrease with age; however, longitudinal studies of serum albumin suggest a modest decline in levels with aging that may be independent of disease. The prognostic value of hypoalbuminemia may be largely due to its utility as a proxy measure for injury, disease, or inflammation. In the community setting, hypoalbuminemia has been associated with functional limitation, sarcopenia, increased health care use, and mortality. In the hospital setting, it has also been associated with increased length of hospital stay, complications, readmissions, and mortality. Other protein markers of nutritional status are being investigated. Prealbumin has received the most attention, as it has a considerably shorter half-life than albumin and may therefore more adequately reflect short-term changes in protein status. Unfortunately, prealbumin otherwise appears to suffer the same limitations as albumin as an indicator of nutritional status.
Serum cholesterol has also been linked to nutritional status. Low cholesterol levels (< 160 mg/dL) are often detected in persons with serious underlying disease, such as malignancy. Poor clinical outcomes have been observed among hospitalized and institutionalized older persons with hypocholesterolemia. A study of community-dwelling older persons found that those in the lowest quartile of serum cholesterol did not differ from others in their nutrient intakes. It appears likely, again, that acquired hypocholesterolemia is a nonspecific feature of poor health status that is independent of nutrient or energy intakes, and that it may better reflect a proinflammatory condition. Of interest is the observation that community-dwelling older persons with both hypoalbuminemia and hypocholesterolemia exhibit the highest rates for adverse functional and mortality outcomes in comparison with those with hypoalbuminemia or hypocholesterolemia alone.
Drugs may modify the nutrient needs and metabolism of older persons. Certain drugs, such as digoxin and phenytoin, even at therapeutic levels, can cause anorexia in the older person. Additional agents that have anorexia as a major potential adverse effect include selective serotonin-reuptake inhibitors, calcium channel blockers (dihydropyridines), H2 receptor antagonists, proton-pump inhibitors, narcotic analgesics, furosemide, potassium supplement, ipratropium bromide, and theophylline. Many drugs are known to interfere with taste and smell (see Oral Diseases and Disorders, Table 42.2) and others may reduce the availability of specific nutrients (Table 24.4).
The nutritional status of the older person can be influenced by a variety of factors (Table 24.5). The absence of single assessment measures that are valid indicators of comprehensive nutritional status has prompted the development of multi-item tools. Older persons in acute- or chronic-care facilities have been extensively studied to identify indicators and predictors of nutritional status, but those in the community setting have been subject to less investigation. Nutrition screening tools for older persons have been widely disseminated, and health professionals are beginning to use such tools for a variety of purposes. Their effectiveness remains to be demonstrated; specifically, we need to learn whether these tools can identify undernourished individuals whose problems are amenable to intervention.
The Nutrition Screening Initiative is a collaborative effort of the American Dietetic Association, the American Academy of Family Practitioners, and the National Council on Aging, Inc. Three interdisciplinary tools to screen for nutrition risk were developed by the Nutrition Screening Initiative to aid in the evaluation of the nutritional status of older persons. The DETERMINE checklist was created to raise public awareness about the importance of nutrition to the health of older persons (see the Appendix and http://www.aafp.org/nsi.xml). This self-report questionnaire is composed of 10 items and is intended to identify potential risks, but not to diagnose malnutrition. The Level I screen, intended for use by health care professionals, incorporates additional assessment items regarding dietary habits, functional status, living environment, and weight change, as well as measures of height and weight. The Level II screen, for use by more highly trained medical and nutrition professionals and suggested for use in the diagnosis of malnutrition, contains all the items from Level I with additional biochemical and anthropometric measures, as well as provision for more detailed evaluation of depression and mental status, as indicated (see http://www.aafp.org/nsi.xml).
The Mini-Nutritional Assessment tool was developed to evaluate the risk of malnutrition among frail older persons and identify those who may benefit from early intervention. More extensive cross-validation studies among healthy older persons have since been completed. This assessment tool requires administration by a trained professional and is composed of 18 items. The assessment includes questions about BMI, mid-arm and calf circumferences, weight loss, living environment, medications use, dietary habits, clinical global assessment, and self-perception of health and nutrition status. A shortened screening version that contains only six items, the short form Mini-Nutritional Assessment (MNA-SF), is now available (see http://www.mna-elderly.com/clinical-practice.htm and reference by Rubenstein, 2001, at the end of the chapter).
Attempts to subdivide the group of nutritional syndromes characterized by loss of weight have been challenging. The nomenclature used implies that these syndromes are distinct, when in practice it is often quite difficult to distinguish one from another, and the syndromes commonly overlap. The presence (cachexia) or absence (wasting) of cytokine-mediated response to injury or disease is at times used, but in examples such as the weight loss from AIDS, there appears that some, but not all, of the loss is the result of inflammation. Some authors note that with cachexia, resting energy expenditure is increased whereas with wasting it is decreased, but this measure is not generally available to most practicing clinicians. Even more confusing are the terms semi-starvation and protein-energy undernutrition, both of which imply that nutritional interventions would be the appropriate correction of the underlying problem, but as will be discussed in the following section, data to support this implication are weak.
The growing prevalence of obesity in America extends to older persons in their 60s and 70s. According to National Health and Nutrition Examination Surveys (NHANES), the prevalence of obesity (BMI ≥ 30) has climbed from 14% to 31% between the years 1976 and 2000. Trends were similar for all age, gender, and racial or ethnic groups (see Table 24.6 and reference by Flegal, 2002, at the end of the chapter).
Excess body weight and modest weight gain (≥ 5 kg or greater) in middle age may be associated with medical comorbidities in later life that include hypertension, diabetes mellitus, cardiovascular disease, and osteoarthritis. Adverse outcomes associated with obesity include impaired functional status, increased health care resource use, and increased mortality. A BMI of 35 or greater is associated with increased risk for functional decline among older persons. Many homebound older persons are now found to be obese. Of interest, poor diet quality and micronutrient deficiencies are relatively common among obese older persons, especially obese older women living alone. Change (increase or decrease) in body weight may be even more strongly correlated with mortality and comorbid conditions like cardiovascular disease or functional limitation. The National Institutes of Health has suggested: “Age alone should not preclude weight loss treatment for older adults. A careful evaluation of potential risks and benefits in the individual patient should guide management.” The focus must be on achieving a more healthful weight to promote improved health, function, and quality of life. A combination of prudent diet, behavior modification, and activity or exercise may be appropriate for selected candidates. For obese older persons with frailty, the emphasis may better be placed not upon weight reduction, but upon preservation of strength and flexibility.
Preventing undernutrition is much easier than treating it. Food intake can be enhanced by catering to food preferences as much as possible and avoiding therapeutic diets unless their clinical value is certain. Patients should be prepared for meals with appropriate hand and mouth care, and they should be comfortably situated for eating. Those needing assistance with eating should be helped. Placing two or more patients together for meals can increase sociability and food intake. Foods should be of appropriate consistency, prepared with attention to color, texture, temperature, and arrangement. The use of herbs, spices, and hot foods helps to compensate for loss of the sense of taste and smell often accompanying old age and to avoid the excessive use of salt and sugar (see Oral Diseases and Disorders. Hard-to-open individual packages should be avoided. Adequate time should be taken for leisurely meals. Title III C of the Older Americans Act has provided for congregate and home-delivered meals for older persons, regardless of economic status. This service is available in most parts of the country, although in some locations there is a waiting list. Adequate access to nutritious and appetizing food should be assured to patients of various cultural backgrounds and in all settings.
Dietary supplements have been widely used in an effort to enhance nutrient intake. Food intake is often decreased by the use of such supplements, but there is usually an increase in overall nutritional intake owing to the nutrient quality and density of the supplements. Standard supplements contain macro- and micronutrients and are available in liquid and bar forms. They are selected on the basis of the patient’s preference and chewing ability and on their cost.
There is also growing interest in the use of micronutrient supplements in health promotion. A wide variety of vitamin and mineral supplements are now commonly available in supermarkets and drugstores. New recommendations for older persons include higher intake of calcium and vitamin D to prevent osteoporosis (see Table 24.2). Folic acid, B6, and B12 can lower homocysteine levels, possibly reducing the risk of coronary artery disease and helping to prevent decline in cognitive function. Immune function may be improved by supplementation of protein, vitamin E, zinc, and other micronutrients. Whether the effects of antioxidants are beneficial is the subject of controversy; it has been suggested that they may help in preventing age-related cataracts and macular degeneration and that naturally occurring dietary antioxidants may reduce cardiovascular disease and mortality. Vitamin E supplementation has not been shown to slow the progression of Alzheimer’s disease or prevent cardiovascular disease and may be associated with higher risk of hemorrhagic stroke. DNA damage from micronutrient deficiencies may be factors in cancer promotion. Since approximately 50% of older persons may also take self-prescribed dietary supplements, it is imperative that the clinician obtain information about the older patient’s use of all supplements. The appropriateness and safety of each supplement should be evaluated, since consumers are often unaware of potential risks and adverse effects of many over-the-counter supplements, and solid evidence in favor of these purported benefits are currently lacking.
A number of agents have been suggested to promote increased appetite or to serve as anabolic aids. Appetite stimulants include the antidepressant mirtazapineOL, an atypical serotonin enhancer, which antagonizes the 5-HT3 receptor, possibly stimulating appetite by that mechanism, but proof of this effect is lacking. Dosing is at 3.75 to 45 mg orally at bedtime, with cautious dose escalation for older persons and reduced dosing for hepatic or renal insufficiency. CyproheptadineOL, a serotonin and histamine antagonist, may also enhance appetite. It is given at a dose of 2 to 4 mg orally with meals, with attention for potential confusion in elderly patients. MegestrolOL is a progestin that stimulates appetite and is given in a daily dose of 320 to 800 mg orally in four divided doses. Improvements in appetite and usually gain in weight have been demonstrated with megestrol acetate; however, it is believed that this weight gain is primarily fat, and clinical benefits to the patient have not been demonstrated. Megestrol acetate in nursing-home populations has been shown to be associated with a higher risk of deep-vein thrombosis. DronabinolOL, a cannabinoid, may stimulate appetite at 5 to 15 mg per m2 per day orally, but it is associated with somnolence and dysphoria in older persons.
Cytokine-modulating agents are experimental. They include anti–tumor-necrosis factor, consisting of antibodies that may inhibit cytokine-mediated inflammation; thalidomide, which may decrease levels of tumor-necrosis factor; and n-3 fatty acids and antioxidants, which may modulate cytokine production.
Trophic agents include human growth hormoneOL, which induces preferential utilization of carbohydrates and fats while preserving proteins and increasing muscle mass. Dosing is 0.125 mg per kg per day intramuscularly, divided in three doses daily. Increased muscle strength and functional capacity, however, are dependent on exercise rehabilitation. Growth hormone is contraindicated in cancer states. Hyperglycemia and fluid retention may be observed. TestosteroneOL is an anabolic androgen that promotes increased muscle protein synthesis with decreased catabolism. Testosterone dosing schemes include 100 to 600 mg intramuscularly every 3 weeks, or 5 mg topical patch or gel daily. Virilizing side effects are expected. OxandroloneOL is another anabolic steroid that increases muscle protein synthesis; it is given at 5 to 20 mg per day orally. Research on all of these trophic agents has failed to demonstrate clinically meaningful benefits to date, but little research has been done.
In the nursing home, unacceptable weight loss, as defined by the Omnibus Budget Reconciliation Act of 1987, is any loss greater than or equal to 5% in the past month or 10% in the past 6 months. The MDS is a functionally based assessment tool performed on admissions to long-term-care facilities that are receiving payments from the Centers for Medicare and Medicaid Services. Sections of the MDS that are related to nutritional status include those assessing cognitive function, mood and behavior, physical function, health condition, oral and nutritional status, dental status, skin condition, and special treatments and procedures, including restorative care for eating and swallowing. Resident Assessment Protocols ensure prompt identification of problems focused on by the MDS. Standards of care dictate that:
Adequate nutrition and hydration should always be provided to the elderly patient unless:
Standards of care and ethical principles also maintain that artificial feeding may be withheld or terminated in accordance with a patient’s advance directive (known as advance care plan in some contexts), with careful consideration of additional comorbidities and futility. Appropriate counseling of the patient and surrogate regarding the consequences of withholding feeding is obligatory. After total cessation of nutrition, several weeks may ensue before death. In this setting, palliative care, including emotional support, is extremely important and complex (see Palliative Care, Legal and Ethical Issues; Eating and Feeding Problems).
■ Flegal, KM, Carroll MD, Ogden CL, et al. Prevalence and trends in obesity among US adults, 1999–2000. JAMA. 2002;288(14):1723–1727.
The prevalence of obesity continues to grow among American adults, according to this latest examination of National Health and Nutrition Examination Survey data from 1999–2000. Increases occurred for men and women in all age groups and for non-Hispanic whites, non-Hispanic blacks, and Mexican Americans. Of particular note, these increases extended into the older age categories.
■ Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). Washington, DC: National Academy Press; 2002.
The latest macronutrient guidelines from the Food and Nutrition Board for the first time specifically address the needs of older persons.
■ Jensen GL, McGee M, Binkley J. Nutrition in the elderly. Gastroenterol Clin North Am. 2001;30(2):313–334.
This comprehensive review of nutrition in the elderly age group provides many of the original references used in this chapter. Topics include changes with aging, nutrient requirements, screening and assessment, nutrition syndromes, and nutritional interventions.
■ Millen BE, Silliman RA, Cantey-Kisler J, et al. Nutritional risk in an urban homebound older population. The nutrition and healthy aging project. J Nutr Health Aging. 2001;5(4):269–277.
Nutritional status of homebound older persons is poor, particularly those of advanced age with comorbid disease. Poor diet quality is nearly universal; more than half of the subjects deviate from recommended standard intakes for at least 13 of the 24 nutritional guidelines. Of interest, fully one third of the homebound older persons studied were obese, with body mass index > 30.
■ Powers JS. Facilitated feeding in disabled elderly. Curr Opin Clin Nutr Metab Care. 2002;5(3):315–319.
This is a review of diseases of undernutrition and their treatment. Changes in physiology, metabolism, and function accompanying aging result in altered nutritional requirements. Designing nutrition therapy to treat malnutrition associated with illness in older patients requires an understanding of the aging processes, a careful setting of treatment goals, and multidisciplinary collaboration.
■ Rubenstein LZ, Harker JO, Salva A, et al. Screening for undernutrition in geriatric practice: developing the short-form mini-nutritional assessment (MNA-SF). J Gerontol A Biol Sci Med Sci. 2001;56(6):M366–M372.
A shortened version of the Mini-Nutritional Assessment, the MNA-SF has 6 questions instead of 18 and can be administered in approximately 3 minutes. The MNA-SF has high diagnostic accuracy relative to clinical nutritional status. Authors recommend that the MNA-SF be administered to patients undergoing comprehensive geriatric assessment or periodic health-risk appraisal as the first step in nutritional screening. The screen is available at http://www.mna-elderly.com/clinical-practice.htm (accessed October 2005).
Gordon L. Jensen, MD, PhD
James S. Powers, MD