Workshop on Disability in America A New Look: Summary and Background Papers (2006) / Chapter Skim
Currently Skimming:
Appendix F Chronic Disease and Trends in Severe Disability in Working-Age Populations--Jay Bhattacharya, Kavita Choudhry, and Darius Lakdawalla
Appendix F Chronic Disease and Trends in Severe Disability in Working-Age Populations--Jay Bhattacharya, Kavita Choudhry, and Darius Lakdawalla
Pages 113-142
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 113... ...
the rising prevalence of disability among chronically ill individuals explains about 60 percent of the rise in disability attributable to trends in chronic illness. Over the past two decades, the rates of severe disability, as measured by limitations in instrumental activities of daily living (IADLs)
|
From page 114... ...
It seems implausible that such changes would have had no effect on disability rates, but how much is the effect? The main aim of this paper is to describe the existing evidence on disability and chronic health trends in the population under age 65 years and to present new estimates of a decomposition of disability trends among working-age populations into two parts: the part of the trend explained by changes in the prevalence of chronic disease and obesity and the part of the
|
From page 115... ...
The optimal policies that need to be implemented to reduce disability will be quite different if disease prevalence is the primary cause than if disability prevalence among the chronically ill is the primary cause. BACKGROUND In this section, we make precise exactly what we mean when we say that someone has a disability.
|
From page 116... ...
-- tend to gather activity limitation information, whereas nationally representative survey instruments, such as the Current Population Survey, emphasize work disability. Data from the 2000 census, however, include elements on long-lasting sensory impairments, ADLs and IADLs, cognitive ability, and work limitations; this recent change attests to an increasing need to understand what disability is, who is affected by disabilities and to what degree they are affected, and possible or likely trends in disability at all ages.
|
From page 117... ...
as opposed to ADLs (personal care)
|
From page 118... ...
presented the most comprehensive work on documenting disability trends in the elderly population. That report presented the summary view of a large group of distinguished researchers on disability in the elderly population.
|
From page 119... ...
They tracked two different measures of disability: personal care and routine needs disability. These are conceptually different from work limitation disabilities, which are also tracked by NHIS.2 Table F-1 shows how disability rates determined from the NHIS data changed between 1984 and 2000.
|
From page 120... ...
(2003a) , based on NHIS data.
|
From page 121... ...
The per capita rate of disability awards was constant for this age group from 1984 to 1990, but it suddenly shot up between 1990 and 1992 as a result of increases in disability insurance payments. The receipt of disability payment alone is unlikely to explain all of the trends in personal care and routine needs disability, because for other age groups the timing of disability award changes does not coincide with the timing of disability growth.
|
From page 122... ...
The literature on disability in this population tends to focus mainly on disability that causes work limitations rather than on other ADL and IADL limitations, which renders much of the literature that we report on here incomparable with our own results reported below. Respiratory diseases such as asthma and chronic bronchitis are increasing in prevalence among the nonelderly population.
|
From page 123... ...
note that a 1 percent biannual decrease in arthritis could result in 4 million person-years of increased activity limitations between the years 2001 and 2049. The overall prevalence of disability (defined as an inability to work)
|
From page 124... ...
Beginning in 1982, they were asked if their health interfered with their major activity, which need not be working. Not surprisingly, therefore, the reported rates of activity limitation among older individuals fell substantially in 1982 because elderly retirees are allowed to report a less strenuous major activity.
|
From page 125... ...
Because more disabled individuals tend to report a less strenuous major activity, the activity limitation question tends to understate the absolute value of changes in disability. On the basis of a respondent's answer to the personal care question, he or she was placed in one of two categories: (1)
|
From page 126... ...
Using Equation F-1, we can write the change in disability prevalence [ ] between t – 1 and t, ∆P Dt , as follows: ∆P Dt = ∆P Dt Ct = 1 P Ct = 1 + P Dt Ct = 1 ∆P Ct = 1 + (change attributable to non-chronically ill pop.)
|
From page 127... ...
, diabetes, hypertension, heart disease, stroke, and obesity.5 The set of jointly occurring conditions that we consider include heart disease and hypertension, diabetes and hypertension, hypertension and stroke; heart disease and stroke, and all conditions interacted with obesity. The last set of interactions is possible because NHIS does not ask about body height or body weight within one of the six randomly assigned condition lists; rather, it asks about these variables in a part of the questionnaire that asks questions of all respondents.
|
From page 128... ...
However, the prevalence of disability among the chronically ill population decreased dramatically, causing a decline in the attributable disability prevalence by 66 cases per 10,000. The bottom row of Table F-2 shows how much of these changes in disability prevalence are attributable to non-chronically ill populations.
|
From page 129... ...
The first data column in each table shows how much of the total change in disability prevalence is due to the change in the prevalence of chronic disease j between 1984 and 1996. The second data column shows how much of the total change in disability prevalence is due to the change in disability rates among those who have condition j in absolute terms.
|
From page 130... ...
If the prevalence of all other chronic diseases had stayed the same while obesity rates increased, as they actually did, our decomposition suggests that the disability rates in this age group would have risen by 20 cases per 10,000 population. This calculation ignores the increase in the prevalence of obese individuals with other chronic diseases.
|
From page 131... ...
Rows with combinations of chronic diseases that contribute less than 10 percent to column totals are excluded. These include obesity and hypertension; obesity and heart disease; heart disease and stroke; heart disease and hypertension; and heart disease, hypertension, and stroke.
|
From page 132... ...
The declining prevalences of hypertension and heart disease, on the other hand, play important roles in the overall decline in the prevalence of disability for this age group. Table F5 shows, with few exceptions, that the disability rates among the chronically ill population declined substantially.
|
From page 133... ...
Thus, the two main sources of increasing disability among those under age 60 years are increases in the numbers of obese individuals and an increasingly disabled chronically ill population. DISCUSSION AND CONCLUSIONS Although previous literature has established rising disability rates in younger populations and falling disability rates in older populations (results that we confirm)
|
From page 134... ...
Even if an increase in disability prevalence meant nothing more than an increase in the set of people unable to perform basic activities like dressing themselves, such increases would be a source of considerable concern, at least to newly disabled individuals and their caretakers. The well-established link between disability prevalence and medical care expenditures by the elderly population heightens the importance of this phenomenon: disability is closely linked to public expenditures on health insurance.
|
From page 135... ...
For example, an increasingly obese populace might produce both more diabetics and a more severely ill diabetic population. Whether these changes in the chronically ill population result in permanent increases in the prevalence of disability and what effect these changes will have on the disability rates of future elderly cohorts are empirical issues that require further research.
|
From page 136... ...
.7 Given these data, we estimate the following logit model of disability prevalence using each year of data available: 1 P[di agei , yeari ]
|
From page 137... ...
Presumably, whatever is left over is explained by trends in other determinants of the prevalence of disability, such as public policy and (mechanically) by disability trends among those with no chronic illness.
|
From page 138... ...
Now, let Et be the portion of disability prevalence that can be explained by the chronic conditions in Ct when they are observed singly. Define Et as a generalization of the first term in Equation F-A-5: K Et = ∑ P[D C k=1 t kt ]
|
From page 139... ...
That is, by ] taking each of the observed chronic conditions singly, Et produces an upper bound on how much disability prevalence can be explained by chronic health conditions.
|
From page 140... ...
Also, as we note above, NHIS does not ask all people about all chronic conditions; rather, it randomly assigns each respondent to respond to one of six condition lists. On the other hand, we can implement the main insight of Equation F-A-11 by expanding the condition set that we consider to include all common combinations of conditions.
|
From page 141... ...
(2000) Contribution of chronic conditions to aggregate changes in old age functioning.
|
From page 142... ...
(1997) Chronic disability trends in elderly United States populations: 1982–1994.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.