Does Being Obese Matter If You Have Medicare?

Abstract & Commentary

By Rahul Gupta, MD, MPH, FACP, Clinical Assistant Professor, West Virginia University School of Medicine, Charleston, WV. Dr. Gupta reports no financial relationship relevant to this field of study.

Synopsis: In the Medicare population, obesity was not associated with mortality, except for those with a BMI of at least 35. However, both overweight and obesity were associated with new or worsening disability within 2 years.

Source: Wee CC, et al. Obesity, race, and risk for death or functional decline among Medicare beneficiaries: A cohort study. Ann Intern Med 2011;154:645-655.

Obesity is a well-established and independent risk factor for cardiovascular disease and mortality in the general population. In 1995, no state in the United States had an obesity rate above 20%. According to a recent report, adult obesity rates increased in 16 states in the past year and did not decline in any state. Now, only Colorado's obesity rate is below 20% at 19.8%.1 More than two-thirds of the states (38) have adult obesity rates above 25 percent. Obesity has long been associated with numerous comorbid conditions. Overweight and obesity are known risk factors for heart disease, diabetes, hypertension, gallbladder disease, osteoarthritis, sleep apnea and other breathing problems, as well as various cancers (uterine, breast, colorectal, kidney, and gallbladder). In addition, obesity is associated with pregnancy complications, hyperlipidemia, menstrual irregularities, psychological disorders, and increased surgical risk. However, it is interesting to note that the effects of obesity on mortality may not be evenly distributed among all adults. For instance, studies looking at the mortality risk due to obesity in the elderly population have produced conflicting results.2 Consequently, it is unclear whether weight control and/or weight loss should be consistently advised for elderly persons. Additionally, it also may be significant to understand the effect of obesity on functional autonomy and disability in this population since much morbidity may result even without a net effect on mortality.

Wee et al conducted a longitudinal cohort study using Medicare Current Beneficiary Survey data to examine and compare the relationship between obesity and all-cause mortality and functional decline among older U.S. adults. The study included data from 20,975 respondents who were aged 65 years or older, interviewed at baseline between 1994 and 2000, and all-cause mortality was calculated from the date of the initial baseline interview until death or April 22, 2008. Also measured was new or worsening disability in performing activities of daily living (ADLs) and instrumental activities of daily living (IADLs) in 2 years.

The researchers found that 37% of the study sample was overweight (body mass index [BMI] of 25 to < 30), 18% were obese (BMI ≥ 30). After adjustment, adults with a BMI of 35 or greater were the only group above the normal BMI range who had a higher statistical risk for mortality. However, in contrast, both overweight and obesity were associated with new or progressive ADL and IADL disability in a dose-dependent manner, particularly for white men and women. In essence, Wee et al found that after up to 14 years of follow-up among Medicare beneficiaries aged 65 years or older, obesity was not associated with all-cause mortality, except for those with at least moderately severe obesity (BMI of 35 or higher). On the other hand, older adults with a BMI even modestly above the normal range were much more likely to develop a new or worsening disability over the following 1-2 years. This association was especially evident for disability related to ADLs. Any differences between white and black older adults were not statistically significant in either of the measurements.

Commentary

Aging often increases vulnerability of individuals to several illnesses such as hypertension, diabetes, coronary heart disease, cancers, and mobility problems linked to arthritis and disability. Now together with an aging population, we are observing an upward shift in obesity rates across the nation. This is further complicated by the fact that increasing inactivity and illness in elderly people commonly results in substantial loss of muscle mass while body fat is relatively preserved or increased. However, several previous studies have documented that the adverse effect of obesity may diminish with advancing age. In fact, some recent evidence suggests that in the elderly, obesity may be paradoxically associated with a lower, not higher, mortality risk thus leading to the term "obesity paradox."3 The complexity of using the most appropriate tools to measure body fat and fat distribution in clinical settings makes it challenging to determine the most valid, practical definition of obesity in the elderly population.4 However, as the above study reveals, functional decline and resulting disability may worsen the quality of life and increase the burden of disease in the so-called "obese" elderly even when there is no measurable effect on mortality. Therefore, a better clinical approach may be to place a greater emphasis on preventing functional decline and muscle loss in older adults through weight-neutral interventions that focus on improving mobility and physical functioning, such as improving muscle strength, balance, and flexibility through physical activity and resistance training.

References

1. Trust for America's Health. F as in Fat: How Obesity Threatens America's Future 2011, July 2011. http://healthyamericans.org/assets/files/TFAH2011FasInFat10.pdf. Accessed July 11, 2011.

2. Heiat A, et al. An evidence-based assessment of federal guidelines for overweight and obesity as they apply to elderly persons. Arch Intern Med 2001;161:1194-1203.

3. Chapman IM. Obesity paradox during aging. Interdiscip Top Gerontol 2010;37:20-36.

4. Zamboni M, et al. Health consequences of obesity in the elderly: a review of four unresolved questions. Int J Obes 2005;29:1011-1029.