Defining Disability

Developing Quality of Care Measures for People with Disabilities: Summary of Expert Meeting

Defining the motivating topic of the day—disability—was the first agenda item. At the outset, meeting participants recognized that their discussion was unlikely to produce a single, agreed-upon definition of disability that would suit all specific purposes. Dr. Clancy anticipated this problem in her videotaped opening comments, noting "...the heterogeneity of this population and the broad range of classifications and definitions of disability. There are more then 47 definitions that are currently in use in federally funded programs, [which] only adds to the challenges." As an example, Table 1 presents two prominent disability definitions from Federal law; they are the definition used by the Social Security Administration (SSA) in determining eligibility for disability benefits (go to and the definition from the 1990 Americans with Disabilities Act (ADA) (go to Obviously, the SSA and ADA definitions serve very different purposes, and therefore it is reasonable for them to differ in emphasis and scope. 

Table 1. Definitions of disability used by the Social Security Administration (SSA) and the Americans with Disabilities Act (ADA) of 1990

SSA: "Inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment(s) which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months."
ADA Sec. 3(2): "The term 'disability' means, with respect to an individual—(A) a physical or mental impairment that substantially limits one or more of the major life activities of such individual; (B) a record of such an impairment; or (C) being regarded as having such an impairment."

To summarize at the outset the results of a complex but insightful introductory discussion, the group agreed that a single, consensus definition of disability is not possible or necessarily desirable. The most appropriate, specific definition of disability will depend on the context in which it is used (e.g., establishing civil rights protections, determining eligibility for income support programs, evaluating different dimensions of health care quality, and so on). Nonetheless, the group identified key principles in defining disability on which there was broad agreement. Participants also agreed that any initiative targeting disability must first start by defining disability for the specific purpose at hand.

AHRQ Disability Definition for Disparities Reports

In her introductory comments, Dr. Clancy stated, "Beginning with AHRQ's 2007 National Healthcare Disparities Report,5 the Agency has used a broad inclusive measure of disability. The measure is intended to be consistent with statutory definitions of disability, in keeping with the fact that factors important to people with disabilities go beyond health." AHRQ bases its NHDRs on data drawn from the large national surveys (e.g., MEPS, NHIS), which were not the focus of the meeting. Nonetheless, to start the discussion and learn lessons from their experiences, Dr. Iezzoni asked AHRQ staff at the meeting to describe their process for defining disability for their annual disparities reports. Before starting this discussion, Ernest Moy, MD, MPH, recognized that AHRQ has not developed "specific quality measures that are unique for individuals with disabilities." Instead, in examining disparities for persons with disabilities, the NHDRs consider the routine services that most people need, regardless of disability.

Dr. Moy noted that, given the range of Federal disability definitions, it took some years for AHRQ analysts to coalesce around a single, standardized measure of disability that would cut across Federal survey databases and could be used for multiple purposes. Frances Chevarley, PhD, briefly described efforts to derive this standardized disability measure. It began with AHRQ's goal of including more information about persons with disabilities in the NHDR and in the National Healthcare Quality Report (NHQR). AHRQ convened a disabilities subgroup of the NHQR/NHDR Interagency Work Group with the assistance of the Interagency Subcommittee on Disability Statistics of the Interagency Committee on Disability Research, which comprised representatives from various Federal agencies. This group was charged with advising AHRQ on measures of disability for the NHDR/NHQR from existing data that (1) could track disparities in quality and access to care for individuals with disabilities and (2) would be comparable across national surveys. The disabilities subgroup adopted the International Classification of Functioning, Disability, and Health (ICF)13 as a model to guide the deliberations (Table 2).

Since the 2007 NHDR, AHRQ has used a broad, inclusive measure of disability that aims for consistency with statutory definitions of disability, such as the 1990 Americans with Disabilities Act (e.g., having a physical or mental impairment that substantially limits one or more major life activities) and other Federal program definitions of disability.5,6,7 For the purpose of the NHDR, people with disabilities are those with physical, sensory, and/or mental health conditions that can be associated with a decrease in functioning in such day-to-day activities as bathing, walking, doing everyday chores, and/or engaging in work or social activities. In displaying the data on disability, paired measures are shown to preserve the qualitative aspects of the data. Limitations in basic activities represent problems with mobility and other basic functioning at the person level; limitations in complex activities represent limitations encountered when the person, in interaction with the environment, attempts to participate in community life. Limitations in basic activities represent problems with mobility, self-care (activities of daily living [ADLs]), domestic life (instrumental activities of daily living [IADLs]), and activities that depend on sensory functioning (limited to people who are blind or deaf). Limitations in complex activities include limitations experienced in work and in community, social, or civic life. These paired measures of basic and complex activity limitations are consistent with ICF's separate activities and participation domains. These two categories are not mutually exclusive: people may have limitations in basic and complex activities.5,6,7

Barbara Altman, PhD, clarified that disability occurs "when the impairment or functioning limitation interacts with the environment and creates ...restrictions in participation." This perspective is consistent with ICF's definition of disability.13 According to Dr. Altman, the measures the subgroup could derive from Federal survey data indicate primarily that individuals were at risk of participation restrictions, depending on their environmental context. As Dr. Altman noted, in its 2007 report The Future of Disability in America, the Institute of Medicine suggested that disability data initiatives throughout the U.S. use ICF's basic multidimensional definition of disability.14

Building on this perspective, the subgroup sorted responses from a series of questions asked in MEPS, NHIS, and other surveys to produce its two measures of disability (limitations in basic and complex activities) for AHRQ's disparities report. Similar definitions and disability measures were also used in the chart book Disability and Health in the United States, 2001-2005 produced by the National Center for Health Statistics.15

Following this presentation of AHRQ's disability definition for the NHDRs, the meeting participants opened the discussion to address a range of concerns about disability definitions, which fell into several different broad categories noted by the section headings used here. 

Table 2. Definition of disability: International Classification of Functioning, Disability, and Health

"Umbrella term for impairments, activity limitations or participation restrictions," conceiving "a person's functioning and disability a dynamic interaction between health conditions (diseases, disorders, injuries, traumas, etc.) and contextual factors," including the social, attitudinal, and physical environments and personal attributes.

Implications of Including the Environment

There was no disagreement among meeting participants about including the environment within a broad definition of disability, as does the ICF. Nonetheless, extensive discussion considered the implications of its inclusion. The basic conundrum is that perceptions of disabilities could change as individuals' environments change. Margaret Stineman, MD, who uses a wheelchair, initiated this discussion as follows:

Stineman: The environment around all of us is constantly shifting. In my work setting, I am not disabled; I am participating. But when I try to get a taxi cab out in the streets of Philadelphia, my participation is really blocked. [This raises the need to consider] the individual in a standard environment, so that a person with a severe impairment who is completely compensated in a particular environment who becomes participation-restricted as they move out of that environment will not be lost in terms of [identifying disability].

Elena Andresen, PhD, concurred with this concern, observing, "As we look at the environment being the link between functional limitation and disability, there is a lot of variation in environment, even for an individual. Disability will depend on which environment they're in." Debra Saliba, MD, MPH, made a similar point, that "in an appropriate environment, [some people with disabilities] would not necessarily show up as disabled with the classic definition."

The group spent time discussing how to assess individual disability holding environmental factors constant (e.g., within a standard environment) and the implications of various approaches. Dr. Andresen mentioned a perspective advocated by some researchers, colloquially called getting down to the 'naked person.'

Andresen: The concept is that if you took away all of the supports, then you could define someone in terms of [the] classic function of human beings. Then when you layer on the other aspects that we're talking about, you would get to environmental supports and health care system issues that might put the person at less or greater risk.

Dr. Andresen did not advocate this specific approach, but she highlighted the need to disentangle the various individual and environmental factors contributing to disability.

Gloria Krahn, PhD, addressed further the implications for measuring disability, suggesting the need to broaden the unit of observation into the person-setting.

Krahn: We're thinking about disability in an ICF framework or more fluid and dynamic that varies across time and setting for people. That puts us into a different place—where the unit of measurement is person-setting. ...However, we might find that it's very difficult to [operationalize] that conceptual construct of person-setting combination.

Dr. Stineman agreed with Dr. Krahn's suggestion to combine the unit of observation, noting that "the person-setting unit is very critical because disability is dynamic, and it's dependent on the environment."

Research Question (RQ): How should variations in the environment be considered in identifying individuals as disabled? How would different approaches affect the specification of health care quality measures for persons with disabilities?


Participants agreed generally with the timeframe suggested by Michael Marge, EdD, who stated that long-term time windows are important in defining disability: "It is important to perceive the health care needs of individuals with disabilities on a long-term basis, in fact throughout their lifetime, because health status is dynamic, and health needs will change over time. Also, the primary disabling condition increases the risk for additional health complications, such as secondary conditions, that exacerbate the individual's health problems and require more complex health care interventions." Whether the SSA's 1-year time window is the right time window for all purposes is unclear, but the basic point is that disability is chronic, not fleeting.

However, Kristi Kirschner. MD, raised concerns about conditions with fluctuating levels of functional deficits. She also highlighted the disabling effects of certain health conditions, such as cancer, not typically considered to cause disability, as follows:

Kirschner: If you look at what brings a lot of people to rehabilitation doctors, it may be a prolonged hospitalization in an intensive care unit. They might have had extensive cancer treatments. They may not be permanently or chronically disabled, but they are very disabled at that point in time. We need to get health care professionals to think about disability in the context of chronic illness or extensive conditions that require prolonged treatment. [Otherwise,] I think we're missing some folks.

RQ: How should fluctuations over time be considered in identifying individuals as disabled? How would different approaches affect the specification of health care quality measures for persons with disabilities?

Need for Clinical Specificity

Depending on the purpose of a quality measure, disability definitions focused specifically on underlying health conditions or functional impairments (as noted in ICF's umbrella definition) rather than on environmental factors may be most useful. Some quality measures will assess treatment (e.g., rehabilitation therapy) of functional impairments or medical interventions for disabling health conditions (e.g., treatment of multiple sclerosis or Parkinson's disease). In these situations, the environmental context may not be as critical as in quality measures evaluating, for example, individuals' participation in community activities.

Setting the Disability Cut Point

During the discussion of the environmental factors, Michael Weinrich, MD, raised a related issue as follows: "Disabled compared with whom? ...You put me in a group of 20-year-old Marines, and I am going to look pretty disabled. Is there an ideal standard, an age-matched ideal standard?"

Vincent Campbell, PhD, approached this concern from the perspective of population-based surveys. One challenge has been to ask meaningful questions about disability given the constraints in numbers of available question slots in certain Federal surveys:

Campbell: We did get two questions: ..."Are you limited in any way, in any activities because of physical, mental or emotional problems?" ...and "Do you now have any health problem that requires you to use special equipment, such as a cane, wheelchair, special bed, or a special telephone?"
We've received criticism for those questions because they suffer from both a lack of specificity and a lack of sensitivity. We have people answering "yes" to either of these, perhaps because they've aged out of the ability to downhill ski, which is an activity limitation for them. Or they have a broken leg, and they use a cane. But I don't know if we would consider those things to be a disability.

Bonnie Strickland, PhD, raised a related issue pertaining especially to children, particularly those with developmental or behavioral concerns.

Strickland: In the National Survey of Children with Special Health Care Needs, a lot of children with special health care needs don't have what their parents would say is a real limitation. When we go back and ask why, often it's because [their condition is] well-managed medically or there is sufficient support within the community. You don't want to miss those children or adults because they're well-managed with support in the community and they're doing just fine. Without those supports, they'd be a person with disability.

Related to Dr. Strickland's point, Dr. Marge asked a provocative question: If an individual is disabled according to our definition but their function is restored through technology or surgery, are they still disabled? In responding to this question, Dr. Stineman drew a distinction between surgery (e.g., hip replacement for someone with disabling arthritis) and restoration of functioning through assistive technology:

Stineman: Surgery is different because you change potentially the anatomic or physiological structure of the human being. If you have changed that structure to the point where there is no longer either a perceived or measurable activity limitation or participation restriction, that person is no longer by our definition disabled. ...[But if someone's function is] restored through a specific technology and that technology breaks down or they can't use it in a different environment, they go right back to being disabled. [In this example, the critical unit is the] person-setting, and technology is part of the setting.

These various issues track closely together: identifying meaningful cut points on a continuum to determine disability, and ensuring that questions and data collection about disability occur in ways that elicit these distinctions.

RQ: Conceptually, what is the cut point on the continuum of functioning and activity participation between having and not having a disability? What is the best way to identify meaningful distinctions? How would different approaches affect the specification of health care quality measures for persons with disabilities?


Closely related to the questions about the disability cut point, M. Elizabeth Sandel, MD, raised a critically important but operationally challenging concern: "People need to define [disability] for themselves, what category they see themselves in. That's not something imposed. It's really empowering the person in clinical settings to define themselves as having a disability and then what their needs are regarding that disability and health care environments."

Dr. Sandel recognized the complexity of allowing individuals to define themselves as disabled or not, including concerns relating to individuals with cognitive limitations. In addition, different cultures have varying attitudes toward disability, raising the potential for inconsistencies between external perceptions and views of individuals. Despite these complexities, Paul Schyve, MD, agreed with the need for patient-centered definitions, linking this perspective to current efforts of The Joint Commission to eliminate barriers to equitable care across diverse subgroups of patients.

Dr. Stineman honed in on the complexities of operationalizing a patient-centered definition of disability relating to a "disconnect" between individuals' self-perceptions and external views, as follows:

Stineman: In our study recently, we found that, among people at the highest level of ADL [activity of daily living] restriction, a certain portion of them... don't see themselves as having a disability. There is a disconnect between the sociological perceptions and whether a person chooses to label themselves... with having a disability....
The objective measurement of an activity limitation, which is something that we do as clinicians, is separate from that subjective perception of the person-centered concept...
The confusion has to do with the fact that the concept of disability itself has both objective and subjective components.... We have to be very careful to distinguish between them.

Cecilia Rivera Casale, PhD, reminded the group that the ultimate goal of health care must be to improve quality of life—an inherently patient-centered and patient-defined concept.

RQ: How could patient-centered perspectives on disability be captured (e.g., within routine data gathering systems)? How should these patient-centered definitions be used, recognizing potential effects of demographic and cultural differences? What are the implications of patient-centered disability identification for the specification of health care quality measures for persons with disabilities?


The discussion about disability definitions ended with general agreement on several key points, including:

  • No single definition of disability will work for all specific purposes.
  • Disabilities are diverse, and considerations relating to one type of disability may not apply to another; similarly, considering disability across the lifespan is essential, but the consequences of disability at different points of the life course might vary.
  • Disability definitions have implications for quality measurement approaches and goals.

Padmini Jagadish, MPP, made another critical point, not necessarily about the definition of disability, but about the implications of specific disabilities for certain quality measures. She used as her example cognitive or intellectual disabilities that affect individuals' abilities to understand certain concepts critical to disease self-management:

Jagadish: We often think of quality of care as something that happens while you're at the doctor's office. But for example, take somebody with dyslexia or an intellectual disability who needs to go home, read, and understand what is on their medication prescription. [When it says, "take the pill 3 times per day,"] does that mean take 3 pills at once or one pill three times a day? ...People with intellectual disabilities and problems with numeracy may have a really hard time understanding that.

Should a quality measure based on presumed adherence to that three-pill regimen consider the implications of intellectual disabilities in assessing providers' performance? Parallel scenarios could be constructed for a range of different disability types.

Current as of September 2010
Internet Citation: Defining Disability: Developing Quality of Care Measures for People with Disabilities: Summary of Expert Meeting. September 2010. Agency for Healthcare Research and Quality, Rockville, MD.