摘要：Objectives. We investigated trends in disability among older Americans from 1988 through 2004 to test the hypothesis that more recent cohorts show increased burdens of disability. Methods . We used data from 2 National Health and Nutrition Examination Surveys (1988–1994 and 1999–2004) to assess time trends in basic activities of daily living, instrumental activities, mobility, and functional limitations for adults aged 60 years and older. We assessed whether changes could be explained by sociodemographic, body weight, or behavioral factors. Results . With the exception of functional limitations, significant increases in each type of disability were seen over time among respondents aged 60 to 69 years, independent of sociodemographic characteristics, health status, relative weight, and health behaviors. Significantly greater increases occurred among non-Whites and persons who were obese or overweight (2 of the fastest-growing subgroups within this population). We detected no significant trends among respondents aged 70 to 79 years; in the oldest group (aged ≥ 80 years), time trends suggested lower prevalence of functional limitations among more recent cohorts. Conclusions . Our results have significant and sobering implications: older Americans face increased disability, and society faces increased costs to meet the health care needs of these disabled Americans. The impact on society of the health and health care needs of older adults has been the subject of growing debate in the United States. This population is expanding more rapidly now that baby boomers (born in 1946–1964) are beginning to reach their 60s. 1 – 3 Heightened concern with our aging population was highlighted by a recent Institute of Medicine report, Retooling for an Aging America: Building the Health Care Workforce . 4 Questions about potential burdens of disability are salient because increased disability in our rapidly growing population of older adults may exert enormous strains on available human and financial resources. Concerns about levels of disability were allayed somewhat by encouraging evidence from the 1980s and 1990s of downward trends in disability. 5 – 13 More recent findings are mixed: data from the National Long-Term Care Survey showed declines, 14 – 16 but other studies suggest that these trends may be reversing, with newer cohorts (including the oldest of the baby boomers) reporting worse health status and more disability than did their earlier counterparts. 9 , 17 , 18 The current epidemic of obesity has been suggested as a contributor to current and future increases in disability. Obesity among US adults has increased dramatically, rising from 11% to 16% in the early 1960s to 28% to 34% by 2000, 19 , 20 resulting in rapidly increasing proportions of overweight, obese, and severely obese members of cohorts now reaching their 60s. 21 , 22 Worse still, forecasts are for levels of obesity as high as 45.4% within 20 years if trends persist. 23 Evidence also suggests that the disability risks associated with obesity may be greater than those experienced 15 to 20 years ago, 9 , 21 , 24 possibly because of earlier onset of obesity (and thus longer lifetime exposure). 25 , 26 The changing racial/ethnic composition of cohorts now reaching their 60s is another potential contributor to changing disability trends. The most rapid growth is projected to be among Blacks and Hispanics, 27 , 28 groups with significantly higher rates of obesity (45% of non-Hispanic Blacks and 36.8% of Hispanics versus 30% non-Hispanic Whites 20 ) and disproportionately lower socioeconomic status—both factors associated with increased risks for functional limitations and disability. 29 , 30 We used data from the National Health and Nutrition Examination Survey (NHANES) for 1988 to 1994 and 1999 to 2004 to examine trends in the prevalence of reported disability for adults aged 60 to 69 years, 70 to 79 years, and 80 years and older, with particular attention to whether trends differed between the youngest and the older 2 groups. For respondents aged 60 to 69 years, the more recent NHANES data included individuals born just prior to the baby boomer generation (1930–1944), providing potential clues to likely trends in the large generation that will immediately follow. We assessed the extent to which differences in reported disability between the 2 survey periods could be explained by changes in the sociodemographic composition of the population, changes in the prevalence of overweight and obesity, or changes in lifestyle or other aspects of health status.
