Despite Longer Life Spans, Fewer Years Are Free of Disease
Increased life expectancy in the United States has not been accompanied by more years of perfect health, reveals new research published in the December issue of the Journal of Gerontology.
Indeed, a 20-year-old today can expect to live one less healthy year over his or her life span than a 20-year-old a decade ago, even though life expectancy has grown.
From 1970 to 2005, the probability of a 65-year-old surviving to age 85 doubled, from about a 20 percent chance to a 40 percent chance. Many researchers presumed that the same forces allowing people to live longer, including better health behaviors and medical advances, also would delay the onset of disease and allow people to spend fewer years of their lives with debilitating illness.
But new research from Eileen Crimmins, holder of the AARP Chair in Gerontology at USC, and Hiram Beltrán-Sánchez, a postdoctoral fellow at the Andrus Gerontology Center at USC, shows that average “morbidity,” or, the period of life spent with serious disease or loss of functional mobility, actually has increased in the last few decades.
“We have always assumed that each generation will be healthier and longer lived than the prior one,” Crimmins explained. “However, the compression of morbidity may be as illusory as immortality.”
While people might be expected to live more years with disease simply as a function of living longer in general, the researchers show that the average number of healthy years has decreased since 1998. We spend fewer years of our lives without disease, even though we live longer.
A male 20-year-old in 1998 could expect to live another 45 years without at least one of the leading causes of death: cardiovascular disease, cancer or diabetes. That number fell to 43.8 years in 2006, the loss of more than a year. For young women, expected years of life without serious disease fell from 49.2 years to 48 years over the last decade.
At the same time, the number of people who report lack of mobility has grown, starting with young adults. Functional mobility was defined as the ability to walk up 10 steps, walk a quarter mile, stand or sit for two hours and stand, bend or kneel without using special equipment.
A male 20-year-old today can expect to spend 5.8 years over the rest of his life without basic mobility, compared to 3.8 years a decade ago — an additional two years unable to walk up 10 steps or sit for two hours. A female 20-year-old can expect 9.8 years without mobility, compared to 7.3 years a decade ago.
“There is substantial evidence that we have done little to date to eliminate or delay disease while we have prevented death from diseases,” Crimmins explained. “At the same time, there have been substantial increases in the incidences of certain chronic diseases, specifically, diabetes.”
From 1998 to 2006, the prevalence of cardiovascular disease increased among older men, the researchers found. Both older men and women showed an increased prevalence of cancer. Diabetes increased significantly among all adult age groups over age 30.
The proportion of the population with multiple diseases also increased.
“The increasing prevalence of disease may to some extent reflect better diagnostics, but what it most clearly reflects is increasing survival of people with disease,” Crimmins said. “The cost of maintaining and providing care for people with chronic conditions is an important part of determining the economic well-being of countries with established social security and government-provided health services.”
Crimmins and Beltrán-Sánchez noted that only delaying the onset of disease through preventive care clearly will lead to longer disease-free lives.
“The growing problem of lifelong obesity and increases in hypertension and high cholesterol are a sign that health may not be improving with each generation,” Crimmins said. “We do not appear to be moving to a world where we die without experiencing significant periods of disease, functioning loss and disability.”
Support for the paper was provided by from the National Institute on Aging and from a Keck NAKFI Healthspan Grant.