2
Definition and Monitoring of Disability

[D]isability no longer means a condition, an incapacity, or lack that belongs to a body, but rather a product of the interactions between self, society, body, and the variety of interactions (from political economies to personal commitments) that they engender.

Sharon Snyder (2006)


In the last half century, the understanding of disability and the language that has been used to describe it have changed dramatically. Certain language—for example, “handicapped worker”—has largely disappeared. More important, the point that Snyder made in the quotation presented above—that disability is not an individual attribute but an interaction between the individual and the environment—increasingly informs discussions of disability and disability policy. The Americans with Disabilities Act and other public policies that are intended to eliminate or reduce environmental barriers to independence and community integration illustrate the point.

Nonetheless, the absence of universally accepted and understood terms and concepts with which to describe and discuss disability continues to be a major barrier to consolidating scientific knowledge about the circumstances that contribute to disability and the interventions that can prevent, mitigate, or reverse it. Its absence hampers clear communication and complicates systematic comparisons across research studies, among groups with different conditions, across nations and different cultures, and over time.

This chapter begins with an examination of concepts of disability.



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The Future of Disability in America 2 Definition and Monitoring of Disability [D]isability no longer means a condition, an incapacity, or lack that belongs to a body, but rather a product of the interactions between self, society, body, and the variety of interactions (from political economies to personal commitments) that they engender. Sharon Snyder (2006) In the last half century, the understanding of disability and the language that has been used to describe it have changed dramatically. Certain language—for example, “handicapped worker”—has largely disappeared. More important, the point that Snyder made in the quotation presented above—that disability is not an individual attribute but an interaction between the individual and the environment—increasingly informs discussions of disability and disability policy. The Americans with Disabilities Act and other public policies that are intended to eliminate or reduce environmental barriers to independence and community integration illustrate the point. Nonetheless, the absence of universally accepted and understood terms and concepts with which to describe and discuss disability continues to be a major barrier to consolidating scientific knowledge about the circumstances that contribute to disability and the interventions that can prevent, mitigate, or reverse it. Its absence hampers clear communication and complicates systematic comparisons across research studies, among groups with different conditions, across nations and different cultures, and over time. This chapter begins with an examination of concepts of disability.

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The Future of Disability in America It endorses the adoption of the conceptual framework published by the World Health Organization (WHO) in 2001 as a means of promoting clear communication and building a coherent base of national and international research findings to inform public and private decision making. At the same time, it identifies several directions for refining and improving that framework to better serve monitoring (surveillance), research, and public policy purposes. The chapter also reviews current disability monitoring activities, evaluates progress since publication of the 1991 and 1997 Institute of Medicine (IOM) reports on disability, and sets forth recommendations for further improvements in monitoring programs. TOWARD A COMMON CONCEPTUAL FRAMEWORK A significant feature of the 1991 IOM report Disability in America was the conceptual framework that it set forth for understanding disability not only as a series of consequences of disease or injury but as a consequence of people’s relationship with their environments—environments that might be supportive of participation in society or that might present obstacles to such participation. Building in particular on the work of Saad Nagi (1965, 1991), it attempted to define a common language for describing and understanding disability and related concepts. The report used the following definitions of stages in the process by which people acquire disabilities or improve their functioning in the context of a particular social and physical environment: Pathology: “interruption or interference of normal bodily processes or structures caused by disease, trauma, or other conditions” Impairment: “loss and/or abnormality of mental, emotional, physiological, or anatomical structure or function; includes all losses or abnormalities, not just those attributable to active pathology; also includes pain” Functional limitation: “restriction or lack of ability to perform an action or activity in the manner or within the range considered normal that results from impairment” Disability: “inability or limitation in performing socially defined activity and roles expected of individuals within a social and physical environment;” also, a “gap between a person’s capacities and the demands of relevant, socially defined roles and tasks in a particular physical and social environment” (IOM, 1991, pp. 79–81) The 1997 IOM report Enabling America relied on the 1991 IOM conceptual framework but made some refinements related, in particular, to clarifying the interaction between the person and the environment and

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The Future of Disability in America the dynamics of the “enabling/disabling” process. The two reports also pointed to secondary health conditions as important and potentially preventable contributors to the progression of health conditions to disability. (As defined in Chapter 5 of this report, secondary conditions are potentially preventable health conditions for which individuals with a primary health condition are at increased risk.) In addition, the two reports included quality of life as an important concept in understanding the impact of health conditions, impairments, functional limitations, and disabilities on people’s sense of well-being in relation to their personal goals and expectations. Although many researchers in the United States adopted the IOM framework, others, particularly in international circles, relied on the World Health Organization’s International Classification of Impairments, Disability and Handicaps (ICIDH) (WHO, 1980). Responding to concerns that the ICIDH was outdated and inadequate to meet current needs for an international classification standard to describe disability, WHO developed a new International Classification of Functioning, Disability and Health (ICF), which was released in 2001 (WHO, 2001). To encourage worldwide acceptance and cultural applicability, WHO developed the ICF framework using a global consensus-building process that involved multiple stakeholders, including people with disabilities. Unlike the ICIDH, the ICF was endorsed in May 2001 by the World Health Assembly as a member of the family of International Classifications, the best known of which is the International Classification of Diseases (ICD). Among the most promising aspects of the ICF framework is its potential to provide a standardized, internationally accepted language and conceptual framework that will facilitate communication across national and disciplinary boundaries and thereby help build a coherent and consistent body of scientific knowledge to inform policies and programs that promote the well-being, independence, and integration of people with disabilities. Consistent with previous disability frameworks, the ICF attempts to provide a comprehensive view of health-related states from biological, personal, and social perspectives (Box 2-1). It describes human functioning and disability as the product of a dynamic interaction between various health conditions and environmental and personal contextual factors. In contrast to earlier frameworks and as reflected in its title, the ICF framework has components that can be “expressed in both positive and negative terms” (WHO, 2001, p. 10). The term “handicap” is no longer used in the English version of the revised classification.1 As in the frameworks presented in the 1991 and 1997 IOM reports and the earlier ICIDH framework, the ICF identifies multiple levels of hu- 1 The French language version of ICF is, however, called the Classification Internationale du Fonctionnement, du Handicap et de la Santé.

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The Future of Disability in America BOX 2-1 Major Concepts in the International Classification of Functioning, Disability and Health Health condition: umbrella term for disease, disorder, injury, or trauma Functioning: umbrella term for body functions and structures, activities, and participation Disability: umbrella term for impairments, activity limitations, and participation restrictions Body function: physiological functions of body systems (including psychological functions) Body structure: anatomical parts of the body such as organs, limbs, and their components Impairment: problems in body function or structure, such as a significant deviation or loss Activity: execution of a task or action by an individual Activity limitations: difficulties that an individual may have in executing activities Participation: involvement in a life situation Participation restriction: problems that an individual may experience in involvement in life situations Environment: the physical, social, and attitudinal environment in which people live and conduct their lives Personal factors: contextual factors that relate to the individual, such as age, gender, social status, and life experiences SOURCE: WHO (2001, pp. 10, 211–214). man functioning and disability: at the level of the body or body parts, at the level of the whole person, and at the level of the whole person who is functioning in his or her environment. These levels, in turn, involve three aspects of human functioning that the ICF terms body functions and structures, activities, and participation. One significant difference in the ICF framework in comparison with earlier frameworks is that the function and disability become generic or umbrella terms in the ICF framework. Thus, the term disability serves—and is used in this report—as an umbrella term for impairments, activity limitations, and participation restrictions. The ICF framework starts with the concept of a health condition, a general term for a disease, disorder, injury, trauma, congenital anomaly, or genetic characteristic. ICF specifically includes aging as a health condition

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The Future of Disability in America (WHO, 2001, p. 212). A health condition is the starting point for the possible development of an impairment, activity limitation, or participation restriction. It usually has a diagnosis as defined and coded either in WHO’s ICD (ICD-10, for its current 10th revision [WHO, 2006]) or in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM IV TR, for its current fourth edition [APA, 2000]).2 The ICF concept of impairment is similar to that of the IOM. The IOM concept of functional limitations shares elements with the ICF concepts of impairment (e.g., for limitations in hearing) and activity limitation (e.g., for limitations in mobility). In contrast, the definition of disability presented in the 1991 and 1997 IOM reports is more specific than that of the ICF. It highlights social roles—the expectations of a society or culture for its members—and the gap that may exist between individuals’ capacities and their performance of social roles in given physical and social environments. The ICF component that most nearly corresponds to this conceptualization is participation restriction, which is defined as “problems an individual may experience in involvement in life situations” (WHO, 2001, p. 10). Restriction is explained as the “discordance between the observed and expected performance,” in which expected performance refers to a “population norm” or standard based on the “experience of people without the specific health condition” (p. 15). Performance is described as “what an individual does in his or her current environment” (p. 15). Life situation is not explicitly defined; but the ICF domains of participation include categories of “domestic life” (e.g., acquiring a place to live and managing a household); “major life areas” (e.g., education and employment); and “community, social, and civic life” (e.g., attending religious services, voting, and participating in professional organizations). Two other concepts defined in the ICF framework as contextual elements are environmental and personal factors. Environmental factors are “all aspects of the external or extrinsic world” that form “the physical, social, and attitudinal circumstances in which people live and conduct their lives” (pp. 10, 213). The domains for environmental factors cover specific features of the person’s actual environment (e.g., the attitudes of community members) that facilitate or hinder a person’s functioning. Personal factors include gender, race, age, lifestyle, habits, social background, and other individual characteristics or experiences that are not classified elsewhere in 2 For example, spinal cord injury has 11 ICD-10 codes that distinguish different types of injury (e.g., fracture of the lumbar spine, fracture of the neck, or the sequelae of a spinal cord injury), whereas multiple sclerosis has a single ICD-10 code. ICD-10 includes codes for mental disorders, and these codes are used in many countries instead of the American Psychiatric Association’s DSM.

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The Future of Disability in America the ICF. Although they are not characterized in this way by the ICF, the negative aspects of certain contextual elements could be included among the risk factors for disability, as defined in the 1991 and 1997 IOM reports. The ICF categorizes most of its major concepts or components into domains (Box 2-2), which are further subdivided into chapter headings and more detailed classifications and codes. The exception is that the ICF includes neither domains nor codes for personal factors. Thus it does not provide a uniform scheme for classifying individual characteristics that may affect the outcome of a potentially disabling condition. To capture more detailed descriptive information about functioning or disability, the framework includes qualifiers that identify the presence and severity of a decrement of functioning.3 Within the activity and participation areas, the ICF advocates the use of qualifiers to assess performance and capacity.4 In essence, the performance qualifiers capture what people actually do in their usual environments, whereas the capacity qualifiers describe the person’s inherent ability to function without assistance. In the ICF manual, WHO acknowledges that the developers of the ICF could not agree on what individual situations should be coded as activities and what individual situations should be coded as participation. Its explanation cites “international variation and differences in the approaches of professionals and theoretical frameworks” (WHO, 2001, p. 16). As a result, the ICF presents a single list of domains for activities and participation and invites users, if they so wish, to differentiate them in their own operational way. Thus some researchers might consider difficulty in preparing meals to be an activity limitation, whereas others might categorize it as a participation restriction. As discussed below, this lack of conceptual specificity is one of the shortcomings in the ICF. 3 In the domain of body function, the qualifier is the presence and degree or severity of a specific impairment rated on a five-point scale: no, mild, moderate, severe, or complete impairment. For body structures, in addition to this severity qualifier, an additional qualifier is used to indicate the nature of a structural change (e.g., partial absence). To cite examples, b1678.3 is the code for “severe impairment in specific mental functions of language” (WHO, 2001, p. 59), and code s730.32 indicates “a severe impairment involving the partial absence of the upper extremity.” 4 A performance qualifier is used to describe what an individual does in his or her current environment, which may present barriers (e.g., the absence of personal help) or supports (e.g., the availability of assistive devices). In contrast, capacity qualifiers describe an individual’s inherent ability to execute a task or an action. The capacity qualifier identifies a person’s highest probable level of functioning without assistance at a given time. Ideally, capacity would be assessed in a standardized or uniform environment that would allow comparisons across research or assessment settings. The same five-point scale used for impairments is used to record the severity of performance or capacity limitations. For example, code d5100.1_ indicates “mild difficulty with bathing parts of the body with the use of assistive devices available to the person.” Code d5100._2 indicates moderate difficulty in the same task without the use of assistive devices or person help.

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The Future of Disability in America BOX 2-2 Components and Domains of Human Functioning in the International Classification of Functioning, Disability and Health Body Function and Structure Body Function: Body Structure: Mental functions Sensory functions and pain Voice and speech functions Functions of the cardiovascular, hematological, immunological, and respiratory systems Functions of the digestive, metabolic, and endocrine systems Genitourinary and reproductive functions Neuromusculoskeletal and movement-related functions Functions of the skin and related structures Structure of the nervous system Eye, ear, and related structures Structures involved in voice and speech Structure of the cardiovascular, immunological, and respiratory systems Structures related to the digestive, metabolic, and endocrine systems Structure related to genitourinary and reproductive systems Structures related to movement Skin and related structures Activities and Participation Learning and applying knowledge General tasks and demands Communication Mobility Self-care Domestic life Interpersonal interactions and relationships Major life areas Community, social, and civic life Environmental Factors Products and technology Natural environment and human-made changes to the environment Support and relationships Attitudes Services, systems, and policies Personal Factors Not categorized SOURCE: WHO (2001, pp. 29–30).

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The Future of Disability in America ADOPTING AND IMPROVING THE ICF The international consensus process used to develop the ICF and its growing use worldwide have provided a significant opportunity to achieve agreement on an international taxonomy for defining, classifying, and measuring function, disability, and health with standard concepts and terminologies. As noted above, an important innovation provided by the ICF is that the nomenclature includes positive descriptions of human functioning and not just the negative consequences of disease or injury, a feature that is very important to the disability advocacy community. The development of standardized measurement instruments based on the ICF would contribute to their adoption in disability research, which would, in turn, help improve data comparability over time and across studies, cultures, and nations. This would aid analyses of the causes and consequences of disability and help guide the development of public policy to benefit people with disabilities, their families, and society at large. In addition, the ICF conceptual framework and classification scheme will support needed research on the contribution of environmental factors to disability. For these reasons, this report uses the ICF conceptual framework and supports its worldwide adoption and use as a standard terminology and classification system, although at times the use of other language employed in laws and policy discussions will be necessary. At the same time, the committee has identified directions for improving and refining the ICF conceptual framework. These directions include developing activity-participation distinctions and measures, adding quality of life as a key concept in understanding disability, developing domains for personal factors, recognizing secondary health conditions related to a primary health condition, further developing environmental factors, and incorporating a dynamic model of the enabling/disabling process. (These areas for improvement are summarized in Box 2-7 in the Recommendations section at the end of this chapter.) Several of these topics are being considered by WHO, United States government agencies, and other groups around the world as part of conferences, working groups, and other activities to refine and apply the ICF. Clarifying Activity Limitations and Participation Restrictions A first and well-recognized aspect of the ICF that needs further development involves the interpretation and categorization of the concepts of activity and participation. Reflecting the difficulty that the ICF developers encountered in differentiating the two concepts, the final ICF document presents them as conceptually distinct with different definitions, but the actual classification scheme provides a single combined list of life areas that

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The Future of Disability in America are not specifically linked to one concept or the other (as displayed earlier in Box 2-1). In an appendix (called an annex), the ICF manual describes how users could, if they so wished, develop operational measures that differentiated between activity and participation. Among the suggestions is the use of the qualifiers of performance and capacity to differentiate among these concepts at an operational level, but the usefulness of this approach has not been confirmed empirically. Several researchers have criticized the lack of a clear operational differentiation between the concepts of activity and participation in the ICF as theoretically confusing and a step backward from earlier disability frameworks (see, e.g., the work of Jette et al. [2003], Nordenfelt [2003], Simeonsson et al. [2003], Barral [2004], Schuntermann [2005], and Whiteneck [2006]). Operational differentiation among concepts and the ability to measure each concept precisely and distinctly is important for clear communication, monitoring, and research. If the differences between these two concepts are not clarified or otherwise resolved in some coherent fashion and if different users distinguish these core concepts in different ways, the goal of a universal and standard language for classifying individuals with respect to the burden of health conditions will remain unfulfilled. For example, Schuntermann (2005), who has worked on implementing the ICF in Germany, notes that severe problems have been encountered with the measurement of activity and participation using capacity and performance qualifiers. He also notes a fear that the lack of an agreed-upon way of differentiating activity and participation may undermine efforts to make valid international and cross-cultural comparisons.5 Researchers are beginning to examine the boundaries of the activity and participation domains of the ICF and exploring ways in which the ICF concepts might be reconceptualized (Nordenfelt, 2003; Perenboom and Chorus, 2003; Okochi et al., 2005; Schuntermann, 2005; Whiteneck, 2006). For example, Whiteneck (2006) has argued that activity is primarily individual (performed alone) and that participation is primarily social (performed with others). Also, activities tend to be somewhat less environmentally dependent and to be a primary focus of medical rehabilitation, 5 With respect to international comparisons, Kapteyn and colleagues (2004) caution that categorization options (e.g., whether an impairment or limitation is mild or severe) may be interpreted differently in different cultures (see also Banks et al. [in press]). They cite Dutch and U.S. data showing quite different distributions of self-reported health status; for example, 6 percent of Dutch respondents categorized themselves in excellent health, whereas 25 percent of Americans did so. This suggests that the “circumspect Dutch appear to run to the center … while the ever optimistic Americans are four times more likely to state that they are in excellent health” (p. 7). Potentially, a process of cultural “norming” could compensate for some cultural and cross-national differences.

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The Future of Disability in America whereas participation restrictions, including discrimination in employment and other areas, offer clear targets for public policy. Nordenfelt (2003) has offered a radical, yet simplifying, suggestion to resolve the current confusion between the activity and the participation domains of the ICF by combining the two domains into a single domain of action. He further proposes that action be qualified in ways that are relevant in the context of rehabilitation or health care but not exclusively so. In contrast to qualifiers contained in the current version of the ICF, he argues that actions could be subdivided in terms of their simplicity and complexity. (Climbing stairs would be a simple action, whereas working would be a complex action.6) Nordenfelt’s analysis has some elements in common with that of Whiteneck, but it lacks the stress on community involvement or social role performance that Whiteneck’s approach maintains, unless some of the subcategories of action could be formulated to re-create it. Although this committee does not endorse any particular approach to resolving the problem, it believes that the lack of operational differentiation between the concepts of activity and participation is a significant deficit in the ICF. Developing the conceptual base for such differentiation or substituting some alternative conceptualization is a key step that needs to be taken to clarify and refine the ICF so that it provides a better foundation for disability monitoring and research. Adding Quality of Life to the Framework The committee is also concerned that the concept of quality of life is not explicitly named or defined as an ICF component or element, although “establishing links” with this concept is mentioned as a future direction in the ICF manual.7 In other documents, WHO has defined quality of life as “the perception of individuals of their position in life, in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards, and concerns” (WHOQOL, 1993, p. 153). Conceptually, quality of life is much broader than the health-related quality of life. Indeed, some measures of health-related quality of life overlap with some measures of impairments or activity limitations. For ex- 6 Nordenfelt also suggests that there are three preconditions for the types of actions that are now included within the activity and participation domains of the ICF. For any action to occur, the individual must have the capacity (i.e., inherent potential) to perform the action. The individual must also have the opportunity to transform inherent potential into action in his or her actual environment. Finally, the person must have the will to perform the action. All actions, whether they are defined as activity or participation, are performed in physical, social, and cultural contexts. 7 A taxonomic annex to the ICF manual depicts a universe of “well-being” as part of the context of the ICF. Well-being is defined as “encompassing the total universe of human life domains … that make up what can be called ‘a good life’” (WHO, 2001, p. 211).

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The Future of Disability in America ample, the Centers for Disease Control and Prevention (CDC) has a 14-item set of questions on health-related quality-of-life, one of which is, “Are you limited in any way in any activities because of any impairment or health problem?” (CDC, 2005a), which is similar to U.S. Census Bureau and other survey questions used to identify people with disabilities. A WHO instrument asks some similar questions, for example, “How well are you able to get around?” Unlike the CDC instrument, however, the WHO instrument also asks, “How much do any difficulties in mobility bother you?” as well as other more general questions such as “How satisfied are you with your abilities?” and “How satisfied are you with your quality of life?” (WHO, 1995; see also WHOQOL [1993] and Bonomi et al. [2000]). These additional questions tap the critical subjective dimension of perceptions and preferences that distinguish quality of life from other concepts. In a paper prepared for an IOM workshop and workshop report (IOM, 2006b), Whiteneck (2006) identified quality of life as a key missing component of the ICF framework, and this committee agrees.8 In addition to refining the ICF conceptual framework to include quality of life, a related area for conceptual and empirical work is clarification of the relationship between quality of life and the existing ICF concepts (see Jette and Badley [2002] for a discussion of conceptual issues). Categorizing Personal Factors An additional area for improvement in the ICF is the categorization of personal factors, which the ICF includes as a concept without a corresponding classification. Personal factors often have an environmentally influenced component (e.g., literacy may be limited by economic, cultural, or other constraints), which complicates the task but which does not eliminate the need for further development of the ICF in this area. This need is recognized in the ICF manual. To the extent that personal factors, such as adherence to treatment recommendations or personality characteristics, are perceived as potentially “blaming the victim” or suggesting that a problem exists with the individual, then they will be controversial (Whiteneck, 2006). To deal with this realistic apprehension, the process of developing categorizations of personal factors should include, in particular, people with disabilities and others who are sensitive to this issue. 8 Whiteneck suggests that qualify of life be added to the ICF as an additional domain. Excluding it from the framework would negate the importance of the individual’s self-evaluation as part of any comprehensive assessment of disability. Treatment of qualify of life as another qualifier would add to the ICF’s conceptual confusion and would, like excluding the concept, diminish its importance.

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The Future of Disability in America ter for Health Statistics. Together with the Medicare Current Beneficiary Survey (which also includes beneficiaries under age 65), these surveys have provided important information on aging, disability, and long-term care, including information about trends in disability among older adults (see Chapter 3 for more discussion of trends). These surveys, however, offer few opportunities for studying participation by older individuals in activities beyond those considered in traditional ADL and IADL measures. As noted above, many key national surveys do not include individuals living in institutional settings. For the purposes of profiling and monitoring disability, the exclusion of people living in residential care settings, such as nursing homes and group homes, is a shortcoming because these individuals often are—by virtue of their qualification for this type of care—significantly limited physically or cognitively, or both. Many of the surveys that focus on older adults include those living in group residential care settings, such as assisted living facilities, but there currently is no standard approach for identifying them (Spillman and Black, 2006). Improving Disability Monitoring Expanding the Goals of Monitoring Disability monitoring serves multiple functions. Altman and colleagues (2006a,b) have highlighted three distinct purposes: To aid in the development and evaluation of service provision programs and policies for people with disabilities, for example, by identifying individuals who need or use housing, long-term care, transportation, assistive technology, or rehabilitation services To monitor functioning, for example, by tracking population-level trends in work limitations or self-care limitations To assess the equalization of opportunities, for example, by comparing employment levels among individuals with and without mobility limitations14 In the past, federal surveys efforts in the United States have emphasized the first two goals. For example, the Survey of Income and Program Participation includes items on the receipt of federal disability and cash assistance from Social Security Disability Insurance and Supplemental Security Income programs. Measures of functioning in the survey have allowed projec- 14 This discussion draws upon materials developed for a meeting of the Washington Group, a city group formed under the auspices of the United Nations to develop internationally comparable measures. For more details, see Altman et al. (2006b).

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The Future of Disability in America tions of the future sizes of these programs (Lahiri et al. 1995; Toder et al., 2002). The aim of tracking health (and, to some degree, functioning) in the population has been a primary aim of the National Health Interview Survey, whereas the Behavioral Risk Factor Surveillance System tracks health conditions and risk behaviors. The Current Population Survey, the nation’s primary data source on employment statistics, includes a measure of work limitations, which can be tracked over time (Burkhauser et al. 2002). In recent years, the removal of barriers to participation by people with disabilities is increasingly being recognized by federal agencies as an important policy goal. For example, as described in Chapter 1, Healthy People 2010 (DHHS, 2000b) includes a chapter on promoting the health of people with disabilities, preventing secondary conditions, and eliminating disparities between people with and without disabilities. Similarly, the Surgeon General’s Call to Action to Improve the Health and Wellness of Persons with Disabilities sets forth the goals of promoting accessible health care and support services for people with disabilities (U.S. Public Health Service, 2005). In addition, the latest strategic plan from the U.S. Department of Health and Human Services calls for increasing the independence and quality of life of people with disabilities (DHHS, 2006c). Unfortunately, despite the advances that have been made since 1991, current survey efforts remain inadequate to assess progress in these stated goals and, likewise, to assess progress in the equalization of opportunity since the passage of the Americans with Disabilities Act and other legislation intended to remove barriers to participation in community life. Information on barriers in public transportation, public accommodations, and telecommunications is not widely or systematically available. The identification of appropriate questions to add to surveys has been challenging. For example, despite a 1998 Executive Order (now expired) to develop an accurate and reliable measure of the employment rate for people with disabilities, the most recent Current Population Survey still includes only a measure of work limitation (McMenamin et al., 2005, 2006). The Bureau of Labor Statistics has undertaken efforts to develop and test measures of disability for the survey, but it has not yet adopted any new measures and is, instead, considering further testing. The approach used to improve the items in the American Community Survey may be useful in this regard (see earlier discussion). Rather than focusing on health conditions or impairments in body systems and structures (i.e., the factors emphasized in the medical model) or introducing circularity of thinking by measuring work disability or limitations in other major life activities, the items relate to limitations in more basic activities such as hearing, seeing, remembering, making decisions, walking, personal care, and doing errands. Although items focusing on an inherent capacity to do an activity rather than actual performance of the activity are preferable for

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The Future of Disability in America assessing unequal opportunities, in practice it is difficult to assess capacity in a brief survey instrument. Consequently, the revised disability items for the American Community Survey (if they are shown to be reliable and valid) may be useful for adoption by surveys for the purpose of identifying individuals at risk for inequality in employment, income, poverty, and health care. Expanding Measures of the Environment The 1997 IOM report recommended that measures of disability reflect a model in which disability (as more narrowly defined in that report) is jointly determined by the characteristics of individuals and their environment. It further recommended that these survey items should be incorporated into ongoing surveys, including the National Health Interview Survey, the Current Population Survey, and the Survey of Income and Program Participation. Several new measures of the environmental components of disability have recently been developed (for a review, see Keysor [2006]), but few have been incorporated into ongoing national surveys. Some surveys include a broad range of demographic, medical, socioeconomic, and behavioral items by which individuals with disabilities can be cross-classified, but they do not measure aspects of the environment that may contribute to activity limitations or participation restrictions. Although certain surveys have adopted a few measures of the use of assistive technologies and others include measures of the family context, measures of the environment otherwise continue to be quite limited. For example, questions about the accessibility of public spaces, barriers in the home or workplace, or insurance coverage for assistive technologies are not routinely included.15 Because these items are missing from national health surveys, investigations into the causes of disability inevitably emphasize only those characteristics that are covered in the surveys, such as chronic health conditions or demographic characteristics (e.g., education). Developing and Implementing Panel Surveys The 1991 IOM report also suggested that a comprehensive longitudinal survey of disability be developed and implemented (Recommendation 9). Such a survey would include specific conditions and a variety of measures 15 In some cases, separate data collection efforts have been mounted to fill these gaps. See, for example, the work of Carlson and Berland (2002), who report highlights from a 2001 U.S. survey of assistive technology and information technology use and need by individuals with disabilities.

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The Future of Disability in America reflecting the personal and social impacts and the economic burden of disability in the United States. Panel studies—those that monitor the same individuals over several years or even decades—are particularly useful in understanding the dynamic nature and natural course of disability, including risk factors for the onset of a disability and recovery from the disability. In 1991, few national panel studies that could be used to study disability trajectories existed. The National Long-Term Care Survey, which began in 1982, and the first Longitudinal Study of Aging (1984 to 1990) provided some national longitudinal data. Both of those studies focused on older adults. In the last 15 years, a number of new panel surveys that include repeated measurement of disability have been undertaken. The Health and Retirement Study, for example, focuses on adults age 50 or over, and the Medicare Current Beneficiary Survey monitors beneficiaries (including adults under age 65 who qualify for Medicare because of a disability) for several years. A second Longitudinal Study of Aging (1994 to 2000) provided a panel survey of health and disability among older adults that was comparable to the one undertaken in the 1980s. These surveys and several smaller panel studies (e.g., the Women’s Health and Aging Study) have provided important insights into the dynamics of disability and risk factors related to disability onset and recovery in late life. As discussed earlier in this chapter, these surveys most often include measures of basic activity limitations (usually ADLs and IADLs) and functional deficits, but little else to understand the nature of the gap between underlying functional abilities and the demands of the physical environment. Moreover, opportunities to study young adults who are aging with disabilities remain limited. Because it has included the full age spectrum, the Survey of Income and Program Participation has served as an important panel resource in the past. In addition to core information on participation in disability-related programs, the survey collects more detailed information about impairments, work limitations, and other activity limitations in topical modules. The “functional limitation and disability” module, for example, which includes questions for adults, young adults, and children, has in the past been administered multiple times to the same panel. The current 2004 panel participants have, however, received this module only once. The proposed reengineering of the Survey of Income and Program Participation by the U.S. Census Bureau (the new Dynamics of Economic Well-Being System; see U.S. Census Bureau [2006a,b]) raises some concerns. If changes in the survey eliminate the topical modules or reduce the collection of data on people with disabilities, the nation’s ability to track gaps in economic well-being for those at risk for disability could be jeopardized. Like the Current Population Survey, it is important that the Survey of Income and Program Participation identify the populations with limitations in basic activities who are at risk for unequal economic well-being.

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The Future of Disability in America Although some recent cross-sectional survey efforts have been geared to understanding children with special health care needs (DHHS, 2004),16 panel studies have not historically been aimed at identifying and monitoring the progress of children with disabilities.17 As part of the assessment of the 1997 Individuals with Disabilities Education Act (IDEA 97), the U.S. Department of Education has launched a series of panel studies to monitor children using special education services: the National Early Intervention Longitudinal Study (focusing on infants and toddlers), the Pre-Elementary Education Longitudinal Study (for children ages 3 to 5), the Special Education Elementary Longitudinal Study (for elementary and middle school youth), and the National Longitudinal Transition Study-2 (the second multiyear study of high school-age children who are moving into young adulthood) (see descriptions of these studies at http://www.ed.gov/about/offices/list/osers/osep/studies.html). (Chapter 4 presents data from the last of these studies.) These panel studies monitor children over several years, including their development; functional status; and participation in social, academic, and family activities. In addition, although they are not an explicit focus, children with disabilities have been included in the department’s Early Childhood Longitudinal Study, which includes two large and overlapping cohorts, one monitored from birth through the first grade and another monitored from kindergarten through the eighth grade (see descriptions of these studies at http://nces.ed.gov/ecls/). Another useful source of information on children with disabilities has been the National Longitudinal Survey of Labor Market Experience, Youth Cohort (BLS, 2005). This Bureau of Labor Statistics survey has monitored a nationally representative sample of 12,686 young men and women who were 14 to 22 years old when they were first surveyed in 1979. Since 1986, detailed information has been collected about the health, functioning, and 16 As defined by the U.S. Maternal and Child Health Bureau, children with special health care needs are “those who have or are at increased risk for a chronic physical, developmental, behavioral, or emotional condition and who also require health and related services of a type or amount beyond that required by children generally” (McPherson et al., 1998, p. 137). This broad definition was developed to help in implementing amendments to the Social Security Act that provided for the development of community-based services to serve children with special needs and their families. 17 In the 1920s and 1930s, three cohort studies in California monitored children’s physical and mental development, and one study (Hauser, 2002) included periodic follow-up data collection into the early 1980s. In the United Kingdom, longitudinal cohort studies include two studies of all children born within brief time frames in 1946 or 1958 as well as later studies of a 1970 birth cohort, a 1991–1992 cohort, and a 2001–2003 group (see, e.g., Wadsworth and Kuh [1997], Plewis et al. [2004], Reilly et al. [2005], and Wright et al. [2006]). These studies have provided substantial information about the interaction of biological phenomena with family, developmental, educational, and other environmental variables that may affect the prevention and management of disease and disability.

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The Future of Disability in America home environment of the children of the women in this sample. For example, 3,315 mothers along with 7,467 children were interviewed in 2002. The state of knowledge about children with disabilities could potentially be enhanced by the National Children’s Study (see http://www.nationalchildrensstudy.gov/). That study, if it is funded to full implementation, would enroll more than 100,000 newborns and monitor them to age 21 (Branum et al., 2003). Beginning even before a child’s birth, the study is designed to collect information on a variety of environmental and genetic variables and assess their effects on children’s birth outcomes and their longer-term health and development. Environment is broadly defined to include natural, human-made, social, and cultural factors. The sample is large enough to allow the study of a number of specific disabilities among children over time. RECOMMENDATIONS Since the publication of the 1991 IOM report Disability in America, many agencies and individuals have taken significant steps to advance the conceptual understanding of disability and to improve aspects of disability assessment and monitoring. At the same time, continued improvements are needed to prepare the country for the future and the challenges that it entails. This section presents the committee’s specific recommendations. The committee recognizes that improvements in the country’s system for measuring and monitoring disability will involve costs, both financial costs and comparability costs as some previously used questions are dropped and new or revised questions are added. Agency budgets will need to be adjusted (at least temporarily) to reflect new costs, trade-offs will have to be made between continuity and improved measures, and areas of policy and other dispute will need to be resolved. For example, some argue that the inclusion of the same questions in different national surveys represents unnecessary duplication and costs (GAO, 2006). In the case of disability measures at least, this committee disagrees with this viewpoint. It is important for surveys not only of health but also of employment, housing, transportation, and other areas to include a core group of disability-related questions, just as they include core questions on race and gender. Otherwise, disparities in key areas of activity and participation will be difficult or impossible to identify and monitor for people with disabilities. Adopting and Improving the ICF Achieving universally accepted and understood terminology, language, and concepts with which to describe and discuss the concept of disability will remove one barrier to progress in disability research and public policy.

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The Future of Disability in America This will not happen immediately but, rather, will involve a long-term process of further movement toward the adoption and application of the ICF conceptual framework combined with continued efforts to refine and improve that framework and to develop tools and methods for applying it. The adoption of the ICF framework and the use of validated measures based on the framework in disability monitoring will support the use of the framework in disability research. This will, in turn, help improve the comparability of research findings over time and across studies, cultures, and nations, which will help build the knowledge base needed to better meet existing needs and prepare the country for the future challenges identified in Chapter 1. The committee recommends that federal agencies involved in disability monitoring explicitly adopt the ICF conceptual framework and support efforts to strengthen it. It further recommends that these agencies cooperate, under the auspices of the Interagency Subcommittee on Disability Statistics of the Interagency Committee on Disability Research (ICDR), to develop and test new measures of disability that correspond to the major elements of the ICF and that fit the specific objectives and needs of each agency. The subcommittee should apply state-of-the-art measurement and research methodologies to evaluate these new measures for their reliability, validity, and relevance to different policy objectives. (Chapter 10 discusses the ICDR in more detail and proposes ways to strengthen it.) Recommendation 2.1:The National Center for Health Statistics, the U.S. Census Bureau, the Bureau of Labor Statistics, and other relevant government units involved in disability monitoring should adopt the International Classification of Functioning, Health and Disability (ICF) as their conceptual framework and should actively promote continued refinements to improve the framework’s scope and utility for disability monitoring and research. The Interagency Subcommittee on Disability Statistics of the Interagency Committee on Disability Research should coordinate the work of these agencies to develop, test, validate, and implement new measures of disability that correspond to the components of the ICF, consistent with public policy priorities. Although it recommends adoption of the ICF concepts, the committee recognizes that the ICF is still a framework under development and that it needs to be refined and strengthened in various areas, as described earlier in this chapter. Box 2-5 summarizes the directions that the committee identified for further work on the ICF. These refinements—combined with a program of further research to evaluate the application of the framework—should help to correct some shortcomings in the classification scheme and respond to concerns that have been discussed by the disability research community

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The Future of Disability in America BOX 2-5 Directions for Further Work on the International Classification of Functioning, Health and Disability As the World Health Organization and others work to improve and refine the ICF, priority areas for attention include clarifying or otherwise resolving the lack of operational differentiation between the concepts of activity and participation; explicitly incorporating quality of life in the framework of key concepts for understanding health and disability and conducting research; developing classifications for personal factors affecting functioning and disability; further developing the classification of environmental factors; incorporating secondary health conditions as an ICF concept; and supplementing the ICF with a dynamic model of factors that influence the movement of individuals among states of functioning or disability. and by ICF users across the world. Although some steps, such as the refinement of the coding or classification of environmental factors and the development of codes for personal factors require the formal modification of the ICF by WHO, the consideration of quality-of-life and secondary conditions in monitoring and research activities can still proceed, as can the development of core measures of ICF concepts as discussed below. The committee recognizes that different disability measures serve different purposes. It therefore does not recommend that a single measure of disability be used in all national disability monitoring programs or that every component of the ICF be equally emphasized in all activities. Specific steps can, however, be taken to move toward greater consistency in disability assessment and monitoring, for example, developing, testing, and then adopting a set of core survey questions. First, for surveys that aim to provide information on the removal of barriers to participation for individuals at risk for unequal opportunity by virtue of their physical, cognitive, mental, or sensory impairments, one priority is the adoption of a uniform set of measures of such impairments of body structure and function. Again, the ICDR can coordinate work to identify a set of core measures of impairment that can be used to measure progress in removing barriers to independent living and participation in community life. The classification scheme of the ICF will be helpful in guiding these efforts, but it does not by itself provide these core measures. For

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The Future of Disability in America activity limitations, the measures proposed for the American Community Survey (as discussed earlier) may be a useful starting point. Second, in addition to refining the classification of environmental factors, further work is needed to measure various environmental contributors to disability, particularly those that contribute to activity limitations and participation restrictions. Important steps include the review of existing measures for their reliability and validity and the development and testing of new items, if necessary. Those measures found to be valid and reliable can then be incorporated into appropriate national surveys. Third, continued refinement is needed of age- or developmentally appropriate measures of disability for children that correspond to the ICF concepts of impairment, activity limitation, and participation restriction (see, e.g., Ogonowski et al. [2004], McConachie et al. [2006], and Simeonsson [2006]). In addition, instruments that identify children with special needs related to their disabilities (e.g., higher than typical rates of use of health care or social services) are valuable, although surveys should continue to identify chronic health conditions that may contribute to disability. Fourth, to the extent that new measures replace old ones in a particular survey, the committee encourages the use of both measures in the years surrounding the transition. This will allow analysts to assess the influence of the wording changes on the survey results. Finally, in addition to the adoption of the new measures by the agencies that are most identified with disability monitoring, the committee encourages other agencies leading or funding relevant national surveys (as listed earlier in Table 2-1) to update their measures to reflect the concepts in the ICF as such measures become available. These agencies include the National Institute on Aging, the Centers for Medicare and Medicaid Services (CMS), and the Agency for Healthcare Research and Quality. Improving the Scope and Quality of National Disability Monitoring Data In addition to adopting the ICF framework, which itself would help harmonize the country’s disability monitoring efforts, the federal government should move in other ways toward a more coherent disability monitoring program. Disability statistics must now be taken piecemeal from multiple surveys to obtain disability-related information on people of all ages and in all living situations. Federal agencies have not harmonized measures across surveys, and surveys pay scant attention to the environmental components of disability. Adopting a common conceptual framework does not in itself correct these shortcomings or fill gaps in existing data. Recommendation 2.2:The National Center for Health Statistics, in collaboration with other relevant federal agencies, should continue to

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The Future of Disability in America improve the scope and quality of data—including longitudinal or panel data—on disability, its causes, and its consequences. These improved data sources should serve as the cornerstone of a new national disability monitoring system. As new measures of the ICF become available, agency coordination through the Disability Statistics Subcommittee of the ICDR will help achieve consistency across surveys. Agencies can collaborate now to develop and test a set of core measures for incorporation into key national surveys, including surveys on housing, employment, income, and other topics that do not now include questions on disability. Action by the CDC, in particular, the National Center for Health Statistics, is critical to an improved disability monitoring system. Priorities include the development of a new panel survey of disability as a supplement to the National Health Interview Survey and enhancements to the Behavioral Risk Factor Surveillance System to provide more comprehensive state-specific estimates of disability. A primary purpose of the panel study on disability would be to track changes in barriers to activity and participation by monitoring the surveyed individuals over time, including as they enter or leave supportive living environments and institutional settings. To secure sufficient representation, the survey would need to oversample children. By monitoring people of all ages over time, a new panel study would also permit investigation of issues related to aging with a disability. In addition, CDC should also consider ways to supplement the National Health Interview Survey framework by surveying individuals living in institutional settings so that the full spectrum of living arrangements can be represented. In developing the panel study, CDC will need to balance the need to reflect new language, concerns, and understandings of disability with the desirability of making some comparisons with the 1994–1995 Disability Supplement. Priorities for enhancements to the Behavioral Risk Factor and Surveillance System include expansion of core disability measures, assessments of disability among children, and measures to track changes in the accessibility of public and private spaces, including schools, health care facilities, and offices. Such measures can be developed first as optional modules and then eventually incorporated into core survey modules. Because employment and economic security are such central issues for the independence and the community integration of people with disabilities, better data on the employment status of and economic opportunities for people with various kinds of limitations are also high priorities. Thus it is important for the Bureau of Labor Statistics to include core disability measures in the Current Population Survey and for the U.S. Census Bureau to include such measures in the reengineered survey in the Dynamics of

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The Future of Disability in America Economic Well-Being System that will replace the Survey of Income and Program Participation. Remedying gaps in knowledge about disability among children is another important direction for a national disability monitoring program. As this chapter and the next make clear, the data on children with disabilities are limited. Moreover, as described in Chapters 4 and 5, policy makers, clinicians, educators, and families lack key longitudinal data on the relationship between childhood conditions, physical and social environments, medical treatments, and other events and the long-term functioning and well-being of children as they move into and through adult life. The inclusion of children in a new CDC panel study of disability and the incorporation of measures of disability among children into the Behavioral Risk Factor Surveillance System would help remedy some of these gaps. The committee’s recommendations to this point focus on the “data production” side of the disability monitoring system. The use of the data for monitoring and other purposes is also important. Although agencies generally make their data available for use by others, it would be helpful for users to have access to some kind of data or information intermediary that would simplify and support user access to the resources of multiple agencies. The NIDRR-supported disability statistics center at Cornell University has taken steps in this direction by preparing guides to disability statistics sources (e.g., the American Community Survey) and data summaries (e.g., annual disability status reports). The center will also develop options for activities to bridge the divide between users and sources of disability data. One possible prototype for such an activity is the Research Data Assistance Center at the University of Minnesota (www.resdac.umn.edu), which is supported by CMS to encourage researchers’ use of the agency’s data by supplying free technical assistance in obtaining and using the data. This chapter has argued for the development of a common conceptual framework based on the ICF framework and a set of actions to strengthen the quality and usefulness of this country’s data on disability and to move toward the development of a coherent, coordinated, ongoing disability monitoring system. Good data are essential to understanding the current situation of people with disabilities, identifying problems, and creating the conditions for the independence and fuller participation of people with disabilities in all aspects of national life. Using data currently available from monitoring programs, the next chapter summarizes trends in disability among Americans in early, middle, and late life.