Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 355

Weight loss in older people

Оглавление

The lower average body weight of older than younger adults is not a function of survival from obesity‐related diseases. On average, people over 75 years of age are more likely to lose than gain weight. For example, in a study that followed 247 community‐dwelling American men age over 65 for two years, men lost on average 0.5% of their body weight per year, and 13.1% of the group had involuntary weight loss of 4% per annum or more. Numerous studies have shown that weight loss in the elderly is associated with poor outcomes, certainly if involuntary, but possibly even when deliberate. The prospective Cardiovascular Health Study, for example, studied 4714 home‐dwelling subjects over 65 without known cancer. In the three years after study entry, 17% of the subjects lost 5% or more of their initial body weight, compared with 13% who gained 5% weight or more. The weight‐loss group had significant increases in total (2.09 × ↑ [95% CI 1.67–2.62]) and risk‐adjusted mortality (1.67 × ↑ [95% CI 1.29–2.15]) over the following four years compared with the stable weight group. The increased mortality occurred irrespective of starting weight and whether or not the weight loss was intentional. The weight gain group had no increase in mortality. In the SHEP study mentioned above, subjects who had a weight loss of 1.6 kg per year or more experienced a 4.9 times greater death rate (95% CI 3.5–6.8) than those without significant weight change. Although mortality was also increased if weight increased more than 0.5 kg per year, the increase was less than that with weight loss (2.4‐ fold vs. 4.9‐fold increase). Of particular note, the adverse effects on mortality of weight loss were present even in the subjects who were heaviest at baseline (BMI ≥31) and were independent of baseline weight. The combination of initially low body weight and weight loss carries a particularly poor prognosis. In the SHEP study, subjects with a low baseline weight (BMI<23.6 kg−2 who lost more than 1.6 kg per year had a mortality rate of 22.6%, almost 20 times greater than the mortality rate of those with a baseline BMI of 23.6–28 kg−2 whose weight remained stable. This interaction is concerning since the tendency for older people to lose weight is variable, with lean individuals probably most at risk. In an older person, unintentional weight loss of 5% or more over 6–12 months is associated with an increased risk of adverse effects, and a loss of 10% or more very likely means protein‐energy malnutrition.12, 17–19

There are many reasons why weight loss in older people has adverse effects. In some cases, weight loss is due to an illness, such as a malignancy. Nevertheless, weight loss and associated undernutrition are significant problems because loss of body weight after age 60 is disproportionately of lean body tissue – that is, sarcopenia – and individuals lose up to 3 kg of lean body mass per decade after age 50. Unlike loss of fat tissue, such a loss of lean tissue has adverse effects. Sarcopenia is associated with metabolic, physiological, and functional impairments and disability, including increased falls and increased risk of protein‐energy malnutrition.20

Pathy's Principles and Practice of Geriatric Medicine

Подняться наверх