Longer, Healthier Lives

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Poor physical functioning is being increasingly compressed into the period just before death.

Life expectancy in the United States has risen sharply in recent decades. Some scholars have worried that the extra years of life could be "low quality" if longer life span is accompanied by longer periods of disability. Fortunately, that does not seem to be the case. In Evidence for Significant Compression of Morbidity in the Elderly U.S. Population (NBER Working Paper No. 19268), David Cutler, Kaushik Ghosh, and Mary Beth Landrum report that although those over the age of 65 are reporting that they have more diseases than those of similar age in the past, "the severe disablement that disease used to imply has been reduced" and "poor physical functioning is being increasingly compressed into the period just before death."

Life expectancy at age 65 increased from 17.5 years to 18.2 years between 1992 and 2005, while "disability-free life expectancy" rose by even more, from 8.8 years to 10.4 years. The result is an increase in the fraction of the lifetime that is disability-free, and a decline of 0.9 years in the expected number of years of disability. The gains in disability-free life expectancy were consistent for men and women, and across races, with non-whites and whites gaining 1.8 and 1.6 disability-free years respectively. Disability declined by roughly 3 percent for people 12 to 24 months from death, by about 6 percent for those who were 25 months or more from death, and by almost 25 percent for those who were eight or more years from death.

The authors analyze data from the Medicare Current Beneficiary Survey, a representative sample of the U.S. elderly population that includes between 10,000 and 18,000 individuals each year between 1991 and 2009. By linking this database to death records through 2008, the authors were able to categorize the health status of nearly 200,000 people at various numbers of years before death. Within 12 months of death, about 80 percent of the elderly had at least one major health condition. Heart disease afflicted about 38 percent of respondents. Three other conditions each affect about one quarter of the respondents: cancer, chronic degenerative diseases like Alzheimer's disease and pulmonary disease, and recoverable acute conditions such as heart attack and stroke.

The authors find that the prevalence of any disability has declined even though the prevalence of major disease has been constant in the elderly population. While the proportion of the elderly population afflicted by acute conditions such as heart disease, stroke, and hip fracture fell from about 40 percent to about 30 percent, the prevalence of chronic disabilities such as Alzheimer's and pulmonary disease, and of disabling but generally non-fatal chronic diseases like arthritis or diabetes, has increased. Although over 60 percent of the elderly report having arthritis or diabetes, the probability of reporting such a condition is not related to remaining years of life.

Disability may result from difficulty in physical functioning, such as the inability to walk a reasonable distance or to carry an object of moderate weight. The incidence of such functional limitations declined by 2.7 percent between 1991 and 2009. Disability may also be caused by an inability to carry out an Activity of Daily Living such as bathing or dressing, or by a problem with an Instrumental Activity of Daily Living such as doing light housework or managing money. The incidence of these disabilities declined by 22 percent.

--Linda Gorman