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Determining Comparable Levels of Functional Disability

Table of Contents: Introduction | Purpose | Methodology | Findings | Policy Implications and Conclusions | References


Long-term care services are used by people who have a wide range of disabilities caused by physical, cognitive, and other mental impairments. In recent years, there has been a growing interest in developing and improving policies and programs to meet the long-term care needs of people with disabilities. A critical issue for policymakers is finding an equitable way to establish eligibility criteria for these programs and benefits.

A desirable social goal is to ensure that people with comparable long-term care needs have equitable access to publicly-supported benefits, regardless of the type of disability they have. Yet the diversity of conditions that create a need for long-term care has led to considerable disagreement about what criteria should be used to determine eligibility for long-term care services (Maslow and O'Keeffe, forthcoming). There is agreement that different measures must be used to assess the impairment of people with physical conditions, as opposed to cognitive and other mental conditions. For example, when assessing whether a person is eligible for long-term care benefits, a woman with severe arthritis is asked about her ability to perform physical tasks, such as dressing and climbing stairs. A man with Alzheimer's disease is assessed for his ability to perform cognitive functions, such as remembering where he lives or what medications he takes. There is, however, less agreement about which measures to use, and little research about the comparability of various measures.

Since the Katz index of Activities of Daily Living (ADL) was developed in 1963, it has gained increased acceptance as an accurate measure of physical functioning. National databases, state long-term care programs, insurers who offer private long-term care insurance policies, federal legislation, and a body of research literature routinely use limitations in the ADLs identified by Katz et al. (eating, bathing, dressing, toileting, transferring, and continence) as appropriate proxies for an individual's level of physical impairment. ADLs can also be proxies for an individual's level of cognitive impairment, depending on the wording of the assessment instrument. For example, assessing whether a person requires physical assistance to perform an ADL primarily measures physical impairment. But assessing whether a person needs prompting or cueing to initiate and complete an ADL primarily measures cognitive impairment.

Physical disability can also be measured with a scale of Instrumental Activities of Daily Living (IADLs), which was developed by Lawton and Brody in 1969. Their IADLs were designed to capture more complex life activities (Rodgers and Miller 1997), and include light housework, laundry, meal preparation, transportation, grocery shopping, using the telephone, medication management, and money management. IADLs are proxy measures that can also be used to identify individuals with cognitive impairments. While cognitive impairment may lead to limitations in the ability to perform all IADLs, those that are generally considered to be most closely related to cognitive impairment are limitations in a person's ability to manage medications, manage finances, or to use the telephone (Spector 1994).

New research by Spector and Fleishman (1998) attempted to develop a single scale of functional disability combining ADLs and IADLs. Using a total of 15 ADL and IADL measures, their research found that there is not necessarily a strict hierarchical relationship between IADLs and ADLs. For example, while ADL limitations generally capture the smallest percentage of persons with disabilities (indicating the most severe levels of disability), "using the telephone," an IADL, had the third lowest proportion of people with limitations. This finding indicates that an inability to use the telephone could constitute a more severe level of disability than many of the ADL measures. Spector and Fleishman also compared the mean hours of help received by persons with zero to 15 ADL/IADL limitations. Raw counts of five to seven limitations were associated with means of 30 to 36 hours of help per week. They conclude that "using a scale that includes both ADLs and IADLs may enable more precise assessment of the level of functional disability...than using ADLs alone."

Ultimately, the ability to perform both ADLs and IADLs diminishes as physical and cognitive functioning declines. Limitations in ADLs and IADLs are now commonly used to estimate the size of the population with disabilities. ADLs and some IADLs also are used to establish eligibility for public and private long-term care programs, services, and benefits, but there has been little understanding of how comparable the disabilities of persons with limitations in IADLs are to persons with limitations in ADLs. The need to find eligibility criteria of comparable severity to established ADL or cognitive impairment criteria was addressed during the debate over the long-term care program proposed in the 1994 Health Security Act (HSA). The eligibility criteria originally proposed by the HSA included:

  • Individuals who required hands-on or standby assistance, supervision, or cueing to perform three or more ADLs over a period of at least 100 days;
  • Individuals with severe cognitive or mental impairments who (for at least 100 days):
  • Attained a score on a standard mental status protocol (appropriate for the person's condition) that indicated severe cognitive or mental impairment, or both;
  • Required hands-on or standby assistance, supervision, or cueing to perform one or more ADL or such number of IADLs related to cognitive or mental impairment, or displayed symptoms of one or more serious behavioral problems that created a need for supervision to prevent harm to self or others;
  • Individuals with severe or profound mental retardation; and
  • Severely disabled children under age 6 who would otherwise be institutionalized.

During the Congressional debate on this legislation, the Senate Committee on Labor and Human Resources revised these eligibility criteria in two ways:

  • Including disabled children under age 6 with severe disabilities or medical conditions that limit functioning "in a manner that is comparable in severity" to the other eligibility criteria of the HSA; and
  • Allowing states to spend a percentage of their funds "to serve individuals with disabilities of comparable severity who fail to meet the eligibility criteria of any single category" (Committee on Labor and Human Resources 1994, emphasis added).

Measures of cognitive impairment included in the HSA were intended to be comparable to its ADL criteria (Jackson and Doty, 1995). Researchers at that time also determined that older persons with at least three out of four IADL limitations (where the four IADLs were medication management, money management, telephoning, and meal preparation) used approximately the same hours of care per week as did people with three or more ADL limitations (Doty, 1998). This standard was not applied to the HSA's eligibility criteria, however, because its implications for persons under age 65 were unclear. Although the HSA was not enacted, refining the eligibility criteria for programs that provide long-term care services and benefits remains an important policy issue.

A new focus on the comparability of different types of disabilities was created with the enactment of the Health Insurance Portability and Accountability Act (HIPAA) in 1996. This law contained several provisions that address long-term care, including standards that long-term care expenses and insurance policies must meet to qualify for favorable federal tax treatment. To take advantage of HIPAA's tax provisions, the definition of a "chronically ill" individual must be met.1 Tax qualified long-term care insurance policies may only provide benefits to individuals who are chronically ill, and long-term care expenses may be deducted only by chronically ill individuals. The definitions contained in HIPAA are similar to the eligibility criteria used in the HSA (limitation in three out of five ADLs), but are somewhat more liberal in allowing access to benefits by persons who need help with two out of five or six ADLs. The HIPAA definition of a chronically ill individual also includes a "similar severity" standard.2


The purpose of this paper is to demonstrate what level of disability would constitute a similar, or comparable, severity to the "two ADL" standard established by HIPAA. Such a standard could be used to trigger eligibility for HIPAA's benefits. Specifically, this research seeks to understand what level of ADL and IADL limitation results in long-term care service use that is comparable to the level of services used by individuals who are unable to perform two ADLs without substantial assistance from another person.


AARP contracted with The MEDSTAT Group to analyze data from the community-dwelling sample of the 1994 National Long-Term Care Survey (NLTCS), a nationally representative survey of the Medicare population age 65 and over. The research attempted to determine what level of disability is comparable to being unable to perform (without substantial assistance from another individual) two ADLs out of six. These six ADLs -- bathing, dressing, toileting, transferring, eating, and incontinence management -- are used in both HIPAA and the original Katz index. Although HIPAA and the Katz index include "incontinence" as an ADL, for this analysis we selected the more restrictive category of "incontinence management," because many persons who experience incontinence are able to manage it without assistance from another person.

The NLTCS was selected because it includes data elements that can be used to derive estimates of functional limitation in this population, including the six ADLs specified in HIPAA. Furthermore, the NLTCS included the components needed to operationalize the HIPAA criteria: receipt of hands-on and/or stand-by assistance in ADLs; inability to perform an IADL without human assistance;3 and a measure of chronicity (90+ days duration) that can be applied to both ADLs and IADLs. Although this analysis conforms to the specific definitions contained in HIPAA, it has broader applicability, given the widespread use of ADL and IADL measures as reliable proxies for disability and the need for long-term care services.

The NLTCS includes data that are crucial to assessing the comparability of alternative functional criteria: hours of care that an individual receives from caregivers, both formal (paid) and informal (unpaid). A focus on hours of care provides an objective and quantifiable method for assessing the comparability of functional disability. It must be noted, however, that the NLTCS contains data only on the population age 65 and older. Thus, the findings of this analysis may not be entirely applicable to service use patterns among younger persons with disabilities.

Step One - Establish Hours of Care

The first step was to establish the total number of hours of care provided by informal and formal helpers to persons in the 1994 NLTCS with two ADL limitations. The hours of care associated with every combination of two ADL limitations were analyzed. Any estimates based on sample sizes below 30 were likely to be statistically unreliable and were excluded from the analysis. Table 1 illustrates the findings of this analysis. It is important to recognize that the hours of care received by people with specific ADL limitations pertain not only to help with those ADLs. For example, an individual who is limited in bathing and dressing does not necessarily receive, on average, 36 hours of assistance per week with only those activities. ADLs are simply proxy measures for a person's overall level of functional disability. An individual who is unable to bathe or dress independently is likely to also need help with IADLs and, in addition, may need assistance with both routine and special health care needs.

The analysis then focused on the two-ADL combination associated with the lowest number of hours of care. This combination was bathing and dressing, which was associated with 36 hours of care per week, on average. The rationale for selecting the two-ADL combination with the lowest hours of care is that an individual can meet HIPAA's definition of chronic illness with any two of six ADL limitations. One should not, therefore, need to meet a more rigorous standard in demonstrating a disability of "comparable severity." This method of analysis should also be relevant to other policy applications, since the eligibility requirements for long-term care services through Medicaid and other long-term care programs generally specify the number of ADL limitations an individual must have to gain program or benefit eligibility, without specifying which ADL limitations an individual must have.

Table 1
Hours of Care Per Week Associated with 2 out of 6 ADL Limitations*

Standard Criteria
Mean Number of Hours
Sample Size
(Unweighted N)
Any 2 ADLs
Bathing & Dressing Only
Bathing & Toileting Only
Toileting & Transferring Only

* Mean hours of care have been rounded.
Source: The MEDSTAT Group, based on data from the 1994 National Long-Term Care Survey.

Step Two -- Identify Alternative Eligibility Criteria

The analysis exploring alternative criteria comparable to the two-ADL standard focused on two groups of persons with disabilities:

  • Those with one chronic ADL limitation who also have one or more chronic IADL limitations; and
  • Those with no chronic ADL limitation who have one or more chronic IADL limitations.

These groups were selected to capture all individuals with IADL limitations who would not be included under a two-ADL criterion. Combining data on individuals with zero or one ADL limitation provided adequate sample sizes for analysis. The analysis considered the eight IADLs that were included in Lawton and Brody's original IADL scale: light housework, laundry, meal preparation, transportation, grocery shopping, using the telephone, medication management, and money management.

The mean hours of care for combinations of zero or one ADL and one through eight IADLs were calculated, and examined for comparability to the bathing-dressing criteria (i.e., 36 hours per week of care, on average). Table 2 illustrates the results of this analysis: people with zero or one ADL limitation who have five, six, or seven IADL limitations are closest in hours of care used to persons who have ADL limitations in bathing and dressing.

Table 2
Hours of Care Per Week Used by Persons with 0 or 1 ADL Limitation (out of Six) by Number of IADL Limitations (out of Eight)*

Number of IADL
Mean Hours of Care
Per Week (Weighted)
Sample Size
(Unweighted N)

* Mean hours of care have been rounded.
** The mean hours of care received by persons with 7 IADL limitations appear to be lower than the hours of care received by persons with 6 IADL limitations. This counterintuitive finding may be an artifact of relatively small sample sizes.
Source: The MEDSTAT Group, based on data from the 1994 National Long-Term Care Survey.

Two ADL/IADL combinations were identified as potential alternative criteria:

  • 0-1 ADL and 5(+) IADLs; and
  • 0-1 ADL and 6(+) IADLs.

These two criteria were chosen for further analysis since their associated mean hours of care either approached or slightly exceeded the mean care hours associated with the bathing-dressing criteria (i.e., 36 hours). The 7(+) IADL standard was not analyzed further because individuals with this level of limitation would be captured among the population with 5(+) or 6(+) IADLs.

Step Three -- Perform Tests of Statistical Significance

Having identified two potential alternative criteria, the final step was to determine whether the estimates of the mean hours of care used per week by persons in the different ADL and IADL categories were indeed comparable. Thus, a t-test was applied to each alternative

IADL criterion and the bathing-dressing criterion. This test measures the difference between means (on hours of care) for independent samples.4 A non-significant t value indicates that the mean of the alternative IADL criterion is not statistically different from the mean of the bathing-dressing criterion. In other words, the level of disability, as measured by hours of services used, is comparable for the two criteria compared. Conversely, a significant t value (greater than 1.96) indicates that the two means are statistically different, and therefore not comparable.


As shown in Table 3, the analysis found that the total hours of care received by individuals with limitations in the ability to bathe and dress is not significantly different from the total hours of care received by individuals who have limitations in zero or one ADL (out of six) who also have limitations in five or six (out of eight) IADLs. As such, individuals who are unable to perform at least five (out of eight) IADLs, whether they have zero or one ADL limitation, can be considered to have a level of disability of "comparable severity" to individuals who are unable to perform two (out of six) ADLs.

Table 3
T-Tests for Differences in Mean Hours of Care Associated with 2 ADL Criteria and Alternative Eligibility Criteria*

Limitation in Bathing & Dressing
Limitation in 0-1 ADL & 5 IADLs
Limitation in 0-1 ADL & 6 IADLs
Mean Hours of Care (Weighted)
Standard Error

* Mean hours of care have been rounded.
Source: The MEDSTAT Group, based on data from the 1994 National Long-Term Care Survey.
Results are significant at the p < .05 level.

Policy Implications and Conclusions

Many legislative proposals to provide long-term care services to persons with disabilities have crafted eligibility criteria based only on limitations in ADLs and limited measures of cognitive impairment. In part, policymakers have focused more attention on ADLs because they are commonly considered to capture more severe levels of disability than do IADLs. Policymakers also are concerned that basing program or benefit eligibility on a limited number of IADL limitations could allow too many individuals into long-term care programs and result in dramatically higher program costs. This concern is based on the higher prevalence of IADL disabilities among older persons. For example, according to the 1994 NLTCS, about 2.3 million older persons are disabled in ADLs, whereas some 4.4 million are disabled in ADLs and/or IADLs.

The findings of this analysis indicate that older persons with significant limitations in five or six IADLs have levels of disability that are comparable to those experienced by people with two or more ADL limitations. By focusing on the hours of care used by people with varying levels of ADL and IADL limitations, this paper presents an objective, measurable standard for comparing the severity of functional disability. While this information should be helpful in developing regulations to implement HIPAA's long-term care provisions, it also could have broader applications. By quantifying the hours of service that are actually used by persons who have five or six IADL limitations and zero or one ADL limitation, this paper demonstrates the importance of including IADL measures in determining program and benefit eligibility. Further research to examine the degree of IADL limitation experienced by individuals with varying levels of ADL limitations would be useful. Additional work in this area could help determine how program and benefit eligibility would be affected by a broader inclusion of IADL criteria.

A substantial number of persons with disabilities are affected by the eligibility criteria used in long-term care programs, services, and benefits. According to estimates from the 1994 NLTCS, 3.0 percent of the Medicare population age 65 and older have severe cognitive impairments. An additional 3.1 percent are disabled in two or more ADLs, and another 1.0 percent meet the zero or one ADL and five or more IADL criteria. This 7.1 percent of the older population with significant disabilities constitutes some 2.2 million individuals. These individuals need access to public programs, private insurance benefits, and other sources of funding to help them pay for their long-term care needs. The responsiveness of public and private policies to the needs of persons with disabilities would be improved by greater attention to the role that IADLs play in functional disability.


Committee on Labor and Human Resources. Health Security Act, Report 103-317, to Accompany S2296, July 19, 1994: 85-86.

Doty, P. Private communication, March 13, 1998.

Jackson, M.E. and P. Doty. "Use of the 1989 National Long-Term Care Survey for Examining Cognitive Impairment Eligibility Criteria," Paper presented at the 25th Public Health Conference on Records and Statistics and the National Committee on Vital and Health Statistics 45th Anniversary Symposium, Washington, DC, July 17-19, 1995.

Katz, S., Ford, A.B., Moskowitz, R.W., Jackson, B.A., and Jaffe, M.W. "Studies of Illness in the Aged: The Index of ADL: A Standardized Measure of Biological and Psychosocial Function." Journal of the American Medical Association,185: 12: 914-919, 1963.

Lawton, M.P. and E.M. Brody. "Assessment of Older People: Self-Maintaining and Instrumental Activities of Daily Living," The Gerontologist, 9: 179-186, 1969.

Maslow, K. and J. O'Keeffe. "What Criteria Should be Used to Determine Eligibility for Long-Term Care Services?" AARP, forthcoming publication.

Rodgers, W. and B. Miller. "A Comparative analysis of ADL Questions in Surveys of Older People." Journal of Gerontology, 52B: 21-36, May 1997.

Shah, B.V., Barnwell, B.G., Hunt, P.N., and LaVange, L.M. SUDAAN User's Manual, Release 5.50, Research Triangle Park, NC: Research Triangle Institute, 1991.

Spector, W.D. and J.A. Fleishman. "Combining Activities of Daily Living With Instrumental Activities of Daily Living to Measure Functional Disability."Journal of Gerontology, 53B: S46-S57, January 1998.

Spector, W.D. "Cognitive Impairment and Functional Disability: Implications for Home Care Eligibility for the Elderly," Paper presented at the annual meeting of the American Public Health Association, Washington, DC, November 1, 1994.


1  A chronically ill individual is defined by HIPAA as any individual who has been certified by a licensed health care practitioner as --

 (i) being unable to perform (without substantial assistance from another individual) at least 2 activities of daily living for a period of at least 90 days due to loss of functional capacity,
 (ii) having a level of disability similar (as determined under regulations prescribed by the Secretary in consultation with the Secretary of Health and Human Services) to the level of disability described in clause (i), or
 (iii) requiring substantial supervision to protect such individuals from threats to health and safety due to severe cognitive impairment.
Interim guidance on interpreting HIPAA, issued by the Treasury Department on May 27, 1997 (Notice 97-31), defined "substantial assistance" as hands-on and standby assistance, which were defined as:  
'Hands-on assistance' means the physical assistance of another person without which the individual would be unable to perform the ADL. 'Standby assistance' means the presence of another person within arm's reach of the individual that is necessary to prevent, by physical intervention, injury to the individual while the individual is performing the ADL (such as being ready to catch the individual if the individual falls while getting into or out of the bathtub or shower as part of bathing, or being ready to remove food from the individual's throat if the individual chokes while eating).
 2  Codified in the Internal Revenue Code, Section 7702B(c)(A)(ii).
 3  The NLTCS measures an individual's ability to perform an IADL as follows: respondents are asked if they perform the activity by themselves. If they report that they do not, they are asked a follow-up question to find out if they could perform the activity if they had to. If they respond no to the first question but yes to the second question, they are not treated as disabled in the IADL. If they reply no to both questions and they say the reason they don't perform the activity is due to a disability or health problem, then they are treated as disabled in the IADL. If, however, the reason they do not perform the IADL is not due to a disability or health problem, they are not considered disabled in the IADL.
 4  Calculation of the t-test statistic involves the use of standard errors. However, because the 1994 NLTCS is based on a complex sampling frame (not simple random sampling), an adjustment for the design effect of sampling was necessary. Non-adjusted standard errors based on complex samples typically underestimate true variation. The tests reported herein were derived from adjusted standard errors calculated using the SUDAAN software package (Shah, Barnwell, Hunt, and LaVange, 1991).

Written by Enid Kassner, Senior Policy Advisor, AARP Public Policy Institute
and Beth Jackson, Project Manager, Research and Policy Division, The MEDSTAT Group
April 1998
© 1998 AARP
May be copied only for noncommercial purposes and with attribution; permission required for all other purposes.
Public Policy Institute, AARP, 601 E Street, NW, Washington, DC 20049

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