Adverse effects of unintentional weight loss and malnutrition—
Among community-dwelling older adults, significant weight loss is defined as 4% to 5% weight loss over 6–12 months or rapid weight loss of >5% in 1 month. For older adults living in skilled nursing homes, the definition of significant weight loss is either ≥10% weight loss over 180 days or ≥5% weight loss over 1 month. Some of the adverse effects of involuntary weight loss and malnutrition include functional decline, increase in mortality rate (9% to 38% within 1–2.5 years), increased risk for hospitalization, increased risk for developing pressure ulcers, postural hypotension, poor wound healing, cognitive decline, and increased risk for infection as a result of poor immune function. Physical signs of malnutrition besides weight loss include peripheral edema caused by protein malnutrition, alopecia, glossitis, skin desquamation, and dry depigmented hair.
Adverse effects of obesity in older adults—
In the United States, approximately 42.5% of women 60–79 years old and 19.5% of women older than age 80 years are obese (BMI >30). For men, 38.1% between ages 60 and 79 and 9.6% of men older than age 80 years are obese. Obesity is associated with an increase in all-cause mortality rate in community-dwelling older adults. However, for geriatric patients living in skilled nursing homes, increase in mortality was found for BMI ≥35 but not for those with BMI between 30 and 35. Obesity can increase the risk for developing hypertension, dyslipidemia, diabetes mellitus, coronary artery disease, stroke, osteoarthritis, and sleep apnea. Increased risk for breast, prostate and colon cancers have also been associated with obesity. Also, obesity has been associated with increased knee pain from osteoarthritis.
BMI, rather than body weight, is a better measure for determining an individual’s nutritional status. BMI adjusts weight in relation to height; however, it does not identify persons who have replaced muscle mass with adipose tissue, nor does it distinguish persons with central obesity. Central obesity is associated with negative health outcomes and thus some researchers believe that waist circumference may be a better measure than BMI for assessment of obesity in older adults.
Skinfold measurement using calipers are prone to many measurement errors and remain primarily a research tool. Bioelectric impedance may prove a better way to assess body composition; however, it is influenced by volume status and also mostly used in research.
The initial laboratory assessment of weight loss should include a complete blood count, glucose, electrolytes, renal and liver function, thyroid-stimulating hormone level, urinalysis, and chest x-ray film. These initial tests should rule out metabolic, endocrine, or infectious causes of weight loss.
Although serum albumin is commonly ordered to assess protein nutrition or status, serum albumin levels have poor sensitivity and specificity as a measure of nutritional health. The half-life of albumin is approximately 3 weeks. Levels respond slowly to adequate nutritional intervention and may never normalize if inflammation is ongoing. Raising the serum albumin with intravenous albumin replacement does not improve prognosis. However, measurement of serum albumin does have clinical value: A low serum albumin, although not a good indicator of nutritional status, may be a powerful predictor of illness severity and mortality.
Prealbumin (transthyretin) has a short half-life of 2–3 days and is more sensitive than albumin in evaluating acute nutritional change. A low level can be used to confirm the clinical impression of poor nutritional status in the absence of inflammation. A progressively rising prealbumin level may help to confirm improving nutritional status; however, the clinical exam remains the best indicator. Serum cholesterol <160 mg/dL is a marker for increased risk of morbidity and mortality but not a good measure of nutrition.
A comprehensive clinical assessment of nutritional status is the most useful way to identify malnutrition, and several assessment instruments exist. The Mini-Nutritional Assessment (Figure 68–1) has become widely used to evaluate nutritional status in geriatric patients. Other screening tools include Seniors in the Community: Risk Evaluation for Eating and Nutrition (SCREEN) (http://www.drheatherkeller.com/index.php/screen/) and the Simplified Nutrition Assessment Questionnaire (SNAQ) (http://www.slu.edu/readstory/newslink/6349).
The Mini Nutritional Assessment (MNA) short form.