Weight, Mortality, Years of Healthy Life, and Active Life Expectancy in Older Adults

Paula Diehr, PhD; Ellen S. O'Meara, PhD; Annette Fitzpatrick, PhD; Anne B. Newman, MD, MPH; Lewis Kuller, MD; Gregory Burke, MD, MS

Disclosures

J Am Geriatr Soc. 2008;56(1):76-83. 

In This Article

Abstract and Introduction

Abstract

Objectives: To determine whether weight categories predict subsequent mortality and morbidity in older adults.
Design: Multistate life tables, using data from the Cardiovascular Health Study, a longitudinal population-based cohort of older adults.
Setting: Data were provided by community-dwelling seniors in four U.S. counties: Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Allegheny County, Pennsylvania.
Participants: Five thousand eight hundred eighty-eight adults aged 65 and older at baseline.
Measurements: The age- and sex-specific probabilities of transition from one health state to another and from one weight category to another were estimated. From these probabilities, future life expectancy, years of healthy life, active life expectancy, and the number of years spent in each weight and health category after age 65 were estimated.
Results: Women who are healthy and of normal weight at age 65 have a life expectancy of 22.1 years. Of that, they spend, on average, 9.6 years as overweight or obese and 5.3 years in fair or poor health. For both men and women, being underweight at age 65 was associated with worse outcomes than being normal weight, whereas being overweight or obese was rarely associated with worse outcomes than being normal weight and was sometimes associated with significantly better outcomes.
Conclusion: Similar to middle-aged populations, older adults are likely to be or to become overweight or obese, but higher weight is not associated with worse health in this age group. Thus, the number of older adults at a "healthy" weight may be much higher than currently believed.

Introduction

The prevalence of obesity and overweight in the United States has grown markedly in recent decades, and two thirds of adults are now classified as overweight or obese.[1,2] In middle-aged persons, obesity is linked to important health problems such as early death, diabetes mellitus, and physical disability.[3,4,5,6] The relationships between weight and mortality are different for older adults. Obesity is an established risk factor for shortened survival in younger but not older adults,[7,8] and relative risks for mortality typically decline with older age.[9] The importance of overweight and obesity as predictors of health status in adults aged 65 and older has also been questioned. For example, one study of older veterans found that being overweight was associated with better health status and quality of life than normal weight.[10] Weight loss advice is routinely given to patients of all ages, even though the literature does not support the idea that being obese or overweight is a strong risk factor beyond age 65. Understanding the relationship between weight and morbidity and mortality into old age has important implications for clinical decisions and public health policy.[11]

Future years of life (YOL), years of healthy life (YHL), and active life expectancy (ALE) are important outcome measures that can be estimated at the person level from longitudinal data.[12] Longitudinal data can also be used to estimate probabilities of transition between states defined according to health and weight. Multistate life table methods can then be used to estimate the expected number of future years spent in each state. The usual life table (with only 2 states: alive and dead) starts with a hypothetical population of 100,000 living persons and estimates, from age-specific death rates, the number who will be alive in the following year, the number alive in the year after that, and so on. A multistate life table is similar, but the years in which persons are alive are tabulated separately to indicate what health and weight state they are in. For example, for a hypothetical cohort of 100,000 healthy normal-weight 65-year-old women, the number who will be healthy and normal weight 1 year later, at age 66, can be estimated. (This method is explained in more detail in the Appendix.)

A related approach was used to estimate the risk of developing obesity from age 35 to 65.[13] That analysis, using data from the Framingham Study, found that the long-term risk of a normal-weight person becoming overweight was 50% and that the risk of becoming obese was 25%. The authors concluded that the future burden of obesity-associated diseases might thus be substantial, although they did not estimate this burden, and their results may not apply to persons aged 65 and older. A similar study found that persons who were obese at age 70 had lower active life expectancy than nonobese persons.[14] That study did not examine transitions between weight categories.

The work presented here uses transition probabilities and multistate life tables to examine concurrent changes in weight and health status over time in older adults. The objective is to further examine the relationship between weight and health after age 65. The question of whether "normal" weight, which is defined without reference to age, is indeed associated with the best health in older adults, as measured according to total, healthy, and active life expectancy, is addressed.

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