Opportunities to Improve Survey Measures of Late-Life Disability: Part I - Workshop Overview

Vicki A. Freedman, Ph.D.
Polisher Research Institute

Timothy Waidmann, Ph.D.
Urban Institute

This report was prepared under contract #HHS-100-03-0011 between the U.S. Department of Health and Human Services (HHS), Office of Disability, Aging and Long-Term Care Policy (DALTCP) and the Urban Institute. For additional information about this subject, you can visit the DALTCP home page at http://aspe.hhs.gov/_/office_specific/daltcp.cfm or contact the ASPE Project Officers, William Marton and Hakan Aykan, at HHS/ASPE/DALTCP, Room 424E, H.H. Humphrey Building, 200 Independence Avenue, S.W., Washington, D.C. 20201. Their e-mail addresses are: William.Marton@hhs.gov and Hakan.Aykan@hhs.gov.

Prepared for the Workshop on Improving Survey Measures of Late-Life Disability, held at the Urban Institute, Washington, DC, May 17, 2005, funded by the HHS Office of the Assistant Secretary for Planning and Evaluation. The views in this overview reflect those of the authors alone and do not represent those of the authors’ affiliations or funding agencies. The authors are solely responsible for any errors or omissions.

INTRODUCTION

Measurement of late-life disability is of interest to policy makers and researchers alike. Valid and reliable measures are necessary to track programmatic eligibility for public health insurance programs such as Medicare and Medicaid and income security programs such as Social Security and Supplemental Security Income. Disability measures are also crucial to accurately projecting the demand for long-term care, to produce actuarial estimates for long-term care insurance, and to understand who is afforded protection under the American with Disabilities Act. Such measures also allow researchers to evaluate the quality of life of older individuals, to understand the causes and consequences of disability in late-life, and to understand the broader public health and policy implications of population aging.

Current measures of late-life disability vary across national surveys. At the same time, most surveys include some version of activities of daily living (ADLs) (Katz 1965, 1970), instrumental activities of daily living (IADLs) (Lawton and Brody 1969), and functional limitations (Nagi 1965, 1991). These measures were initially developed for various clinical purposes during the 1960s and 1970s, and became widely adopted as self-reported items in national surveys during the 1980s and 1990s. Surveys that have maintained identical question wording from year to year have been able to provide two decades worth of evidence on trends in the prevalence of late-life disability (Manton and Gu 2001; Schoeni et al. in press). In addition, panel surveys have provided important insights into disability trajectories, including recovery and decline, and hierarchical patterns (Crimmins and Saito 1993; Dunlop et al. 1997; Mor et al. 1994).

Recent advances in conceptual thinking and measurement of disability provide new opportunities for national surveys to expand upon the array of scientific and policy questions that may be answered with survey data. For example, the addition of vignettes could facilitate comparisons of disability measures across groups and countries with different conceptual understandings of disability (Kapteyn et al. 2004). Moreover, the addition of measures of physical functioning (including performance measures), of assistive technology and the environment, and in time use and participation by older adults would allow analysts to more fully understand the reasons for population-level changes in disability prevalence. Currently, it remains unclear, for example, to what extent changes in disability that occurred during the 1990s reflect changes in underlying functioning, changes in the physical environment of older adults, or shifts in the use of assistive technology (Freedman et al. 2003). Similarly, it remains unclear if declines in IADLs reflect changes in underlying functioning, the physical environment, or changes in the nature of the tasks as a result of technological conveniences (Spillman 2004). Improved measures of the components of disability would also further understanding at the individual level of the physiology of functional loss and recovery (Guralnik et al. 1989), the accommodation process (including use of assistive technologies, personal care and behavioral changes; see Agree 1999), and interventions to enhance independence and participation (Freedman et al. 2005).

Although measurement of work disability has recently been explored by a Committee of the Institute of Medicine (Mathiowetz and Wunderlich 2003), recent advances in the measurement of late-life disability have not been systematically reviewed. To address this gap, the Office of the Assistant Secretary for Planning and Evaluation of the Department of Health and Human Services (HHS) convened a workshop in May 2005 to bring together disability measurement and policy experts to re-think measurement issues around late-life disability in light of national survey efforts. Specifically, the meeting will seek to address two questions:

• Are our current measures of late-life disability meeting the needs of researchers and policy makers?
• How can we improve measures of late-life disability within our current surveys?

This issue brief provides background information on issues that will be raised at the workshop. We include a brief review of disability measurement issues and offer a framework for thinking about disability measurement that will shape the workshop panels and presentations.

EXISTING DISABILITY MEASURES

National surveys most often include variations in three sets of disability measures: ADLs, IADLs, and functional limitations. Each of these measures was developed for clinical purposes and originally intended to be filled out by a professional evaluating an older person’s capabilities. For example, Katz (1963, 1970) developed the original ADL index to assess the rehabilitation potential of hospitalized geriatric patients. The index was to be assessed by means of a series of questions and observations of the patient’s ADL status during the previous two weeks. The observer determined whether another person assisted the patient (through supervision, direction, or personal assistance) or whether the patient functioned alone. The original IADL scale, developed by Lawton and Brody (1969), was intended to facilitate communication about clients’ everyday functional competence among different personnel and agencies involved in treatment plans. They proposed “representative” activities for consideration: women were to be evaluated by their ability to shop, cook, and do laundry whereas men were to be evaluated by their performance in transportation and handling money. The original functional limitation items developed by Nagi (1965) were used to identify social security disability applicants who had the potential for rehabilitation. The instructions directed a team of medical evaluators to assess and the applicant to self-assess his or her maximum capacity and the physical requirements for the applicant’s job (both using a numeric scale from 0 for “No Ability” to 7 for “No Restriction”).

The extent of variation across national surveys in ADL and IADL items has been previously noted (Cornman et al. in press; Freedman et al. 2004; Gregory 2004; Rodgers and Miller 1997; Wiener et al. 1990). Here we illustrate the point in Table 1 with a summary of ADL and IADL questions, respectively, for 9 current national surveys (see detailed questions provided in Appendix Table 1 and Table 2).

For ADLs, some surveys ask about difficulty and the use of help and assistive devices; others ask only a subset of these concepts. Most surveys ask about difficulty (or in one case a “problem”) with daily activities, but only three surveys explicitly refer to difficulty without help or equipment. Most surveys ask about help, but one asks about needing help, another about help in the last week, and another about help in the last month. Two surveys ask about both hands-on help and supervision. Questions about the use of equipment also vary widely, with some surveys asking about equipment use in the series of ADL questions and other surveys asking about it separately. The number of ADL activities mentioned in the surveys varies from three to nine.

With respect to IADL activities, similar variation is evident. Five of the nine surveys ask about both difficulty and help with IADLs; however, language around the reason for the difficulty/need for help varies (e.g., because of a health or memory problem; because of a health or physical problem; because of a physical or mental health condition) as does the number of activities mentioned (ranging from two to ten).

A similar kind of variation is evident across national surveys in functional limitation items. These questions generally taking one of two forms, described elsewhere as “neutral” and “leading” (Freedman, Aykan, and Kleban 2003): does the older person have any difficulty carrying out basic body movements and how much difficulty does the older person have carrying out basic body movements? Physical tasks vary but generally include both upper (reaching up, reaching out, grasping) and lower (bending, lifting and carrying, climbing stairs) body movements.

Other common items included in national surveys to assess late-life disability include measures of work disability (for details see Mathiowetz and Wunderlich 2003), sensory impairments (e.g., difficulty with vision or hearing), and self-reports or tests of cognition (Herzog and Rodgers 1999). More recently surveys have begun to ask about difficulty with valued activities. For example, the National Health and Nutrition Examination Survey (NHANES) and National Health Interview Survey (NHIS) ask about the amount of difficulty with leisure activities such as: going out to things like shopping, movies, or sporting events; participating in social activities [visiting friends, attending clubs or meetings or going to parties]; and doing things to relax at home or for leisure [reading, watching TV, sewing, listening to music].

OPPORTUNITIES TO IMPROVING EXISTING DISABILITY MEASURES

Recent advances in disability theory and measurement provide new opportunities for surveys to improve upon existing disability measures. To facilitate discussion and set the stage for workshop presentations on innovations in measurement, here we provide background in three areas: advances in conceptual thinking about disability; efforts to standardize disability measures across groups and countries; and efforts to understand and improve measures of the underlying components of disability--physical functioning, technological accommodations, the environment, and the specific tasks in which older people engage.

Advancements in the Conceptual Understanding of Disability

Over the last several decades, several overarching perspectives have emerged that guide efforts to enumerate the extent of disability in the United States population. Over time these perspectives have evolved from a strictly medical model to one that recognizes the social and environmental context of disability (Fujiura and Rutkowski-Kmitta 2001). The traditional medical model emphasizes the individual’s medical condition or organ impairment underlying the disability. In contrast, Nagi’s functional limitation model (Nagi 1965, 1991; Verbrugge and Jette 1994) and the original International Classification of Impairments, Disabilities, and Handicaps (ICIDH) make explicit the social context of disability.

Nagi’s functional limitation model emphasizes four stages, first, pathology, or compromised organ function due to chronic or acute conditions or injury; second, impairment, or the loss of system function; third, functional limitations, defined as limitations in physical or mental actions due to the loss in system function; and finally, disability, or the inability to carry out socially defined roles or activities. In this paradigm, disability exists if the functional loss is sufficient to restrict an individual from performance of a socially defined role. Similarly, the ICIDH depicted a four-stage sequence of disorder, impairment, disability, and handicap. In this approach, disability is defined as a limitation in activity, whereas handicap refers to a disadvantage relative to others that is caused by an activity limitation.

The concepts embedded in these models are evident in many of the disability measures that are in national surveys today. For example, concepts embedded in the classic medical model are evident in questions in the NHIS and the Survey of Income and Program Participation, which allow adults with limitations in activities to be classified according to conditions. Similarly, the most recent Census asks about “the presence of a condition that substantially limits one or more basic physical activities such as walking, climbing stairs, reaching, lifting, or carrying.” Nagi’s influence is readily seen in the adoption of functional limitation items on most national surveys.

More recently, the International Classification of Functioning, Disability and Health (ICF) has linked health conditions to participation in society through the influence of body functions and structure, activities, the environment, and personal factors (World Health Organization 1999). Unlike earlier frameworks, the ICF explicitly links health dimensions to participation in society and makes explicit contextual factors--the individual’s health condition, the environment, and other personal factors--that may influence and interact with the process by which body functions and structures relate to participation.

Several recent measurement-development projects build on these conceptual frameworks. Based on Nagi’s disablement model, for example, Jette and colleagues (2002a, 2002b) developed questionnaire items that assess late-life function and disability. Similarly, Gill et al. (1998) and Jette (1994) have demonstrated the distinct but complementary nature of measures of “difficulty” (difficulty with task) and “dependence” (need for help with task). Freedman and Agree (2005) highlight the role of assistive technology in the disablement process by making explicit the concepts of the environment and accommodations (i.e., the use of help, assistive technology, or changes in behavior). And, drawing upon the conceptual elements of the ICF model of disability, The Washington Group has proposed the development of internationally comparable census measures of disability to assess equalization of opportunity (Madans et al. 2004).

Efforts to Standardize Measures Across Surveys and Countries

The Federal Government has long recognized the value in attempting to introduce some level of standardization of disability measures into national survey efforts. For example, in 1988 the Forum on Aging-Related Statistics systematically examined surveys measuring ADLs to identify reasons for variation in estimates (Wiener et al. 1990). Most recently, the Federal Interagency Forum on Aging-Related Statistics has recommended that surveys that have ADL, IADL, and other measures of physical functioning use consistent wording and response categories whenever possible. Standardization of disability questions across countries has also received attention, as illustrated in a recent draft position paper by the Washington Group (Madans et al. 2004). The authors make the important point that measures may need to vary to suit different purposes, but they also argue for the need to standardize disability questions across countries as much as possible.

Related to this notion of standardization is the challenge of identical words not providing a shared meaning for all groups. For example, the term ‘disability’ or even “difficulty’ may not carry the same meaning across countries or across cultures within a country. The use of anchoring vignettes has received recent attention as a means of improving comparisons across groups or countries of survey-based measures of health (Salomon et al. 2004; King et al. 2004) and disability (Banks et al. 2004; Kapteyn et al. 2004; Tourangeau et al. 2005). The approach involves including in surveys a self-assessment of respondent’s health (or disability) and an assessment of several hypothetical persons’ health, as described in short vignettes. The anchoring vignettes for measuring self-care in the World Health Study, for example, are shown in Table 2. Because the vignettes measure the variation in concepts for a set of specific circumstances, they answers may be used to standardize or “anchor” differences in perceptions across groups or countries (see King et al. 2004 for a description of methodological approaches).

Advances in Measuring the Underlying Components of Disability

Disability is defined at the intersection of several key concepts: an individual’s capacity to physically and cognitively function, the physical and social environment, the tasks that individuals choose to carry out, and the accommodations they make to carry them out (e.g., use of assistive devices, use of personal care from another person, or changes in their behavior). Advances in the understanding and measurement of each of these components have taken place over the last decade.

Physical functioning. There are two basic approaches to measuring physical functioning--that is the ability to function without help or the use of assistive devices. Subjective, self-reported measures of functioning and objective, performance-based measures appear to measure different, although related, constructs (Reuben et al. 1995); however, when combined they appear to provide more precise predictors of mortality and future hospital costs (Reuben et al. 2004a, 2004b).

Physical performance measures involve an individual performing a movement or task according to a standardized protocol and a trained observer rating the performance using objective, predetermined criteria (Guralnik et al. 1989, 1996; Halter and Reuben 2000). Batteries have been developed to measure the basic components of functioning (e.g., strength, balance, coordination, flexibility, endurance) as well as physical movements (e.g., walking) and goal-oriented functions (e.g., ADLs and IADLs). NHANES, for example, includes performance measures of balance and strength in its mobile exam center protocol. Further work is needed to promote standardization of performance measures in research settings (Guralnik and Ferrucci 2003).

Self-reports of functioning include Nagi’s functional limitations items and other self-assessments of the ability to function without assistance. More recently, Sayers et al. (2004) report high correlations between performance-based measures and new self-reported measures of functioning from the Late-Life Function and Disability Instrument (LLFDI) (Haley et al. 2002). The LLFDI subscale asks about difficulty without help or special devices (none, a little, some, quite a lot, cannot do) with 32 functions (including, for example, unscrewing the lid off a previously unopened jar without using any devices; running half a mile or more; making a bed). They conclude that the functioning component of the LLFDI is an acceptable substitute for performance-based measures when self-report is a preferred mode of data collection format.

There are a number of challenges in incorporating measures of physical functioning into national surveys. In December 2003, the National Institute on Aging sponsored a meeting on physical functioning to review existing protocols and discuss issues related to their use in population-based studies (Suthers and Seeman 2004). Methodological challenges were outlined for both self-reports and performance-based measures. For example, both types of measures would benefit from enhanced discriminatory capability of measures. Other issues raised specifically about performance measures related to the feasibility of administering tests in the home, the need for systematic training of observers, and need to consider possible bias associated with differential refusal rates.

Measures of time use and participation. Although ADLs and IADLs have been used widely in research and policy making activities and have advanced our understanding of functioning in late-life, it is unclear the extent to which these measures--and IADLs in particular--reflect meaningful activities to older Americans today.

Information on time use can help identify how older Americans are spending their time. Time use information is typically collected either using “stylized” questions about time (e.g., last week how many hours did you spend _____) or using time use diaries (e.g., At 5 AM what were you doing? For how long?). The Bureau of Labor Statistics has recently revised the American Time Use Survey (Horrigan and Herz 2004), which takes advantage of computer-assisted telephone interviewing technology and time use diaries.

The reliability and validity of various strategies for collecting time use data has been explored. Juster et al. (2003), for example, find that similar estimates of labor market work hours and of historical trends are produced by diaries and stylized questions. Most often information on time use is reported in broad categories (e.g., unpaid work, paid work, self-care, active and passive leisure activities). For example, research in Canada suggests that older adults are active and engaged (Fast and Frederick 2004) and cross-national comparisons find similarities in the age patterns of activities (Gauthier and Smeeding 2003).

Measures of the environment and technological accommodations. Over the last decade awareness has grown that disability cannot be assessed outside of the physical and social environment and the accommodations individuals make to carry out purposeful tasks and roles (Brandt and Pope 1997; Satariano 1997). Current measures of disability rarely acknowledge the environment in which tasks take place. For example, questions about difficulty bathing generally do not address whether an individual bathes in a stall shower or a bathtub or whether they hold on to a grab bar or use a shower stool.

A recent project funded by the Office of the Assistant Secretary for Planning and Evaluation in HHS seeks to begin to remedy this gap by developing and evaluating new measures of assistive technology use and the home environment (Freedman and Agree 2005). The purpose of this project was to develop, pilot, and disseminate an instrument to be used in national surveys to collect information on assistive technology and environmental modifications used in both the home and workplace. The instrument has been extensively cognitively tested and then pilot tested under the direction of the National Center for Health Statistics by telephone with 360 older adults (ages 50 and older) living in the community. The final instrument consists of brief modules that may be adopted in whole or in part by national surveys. Concepts that have been measured include the use of assistive technology, intensity of use, the home environment, difficulty with ADLs residual to technology use, and the effectiveness of assistive devices on several quality of life dimensions.

Other instruments have been developed to assess barriers in the community that may impede mobility. For example, Shumway-Cook et al. (2003) have developed an instrument to measure environmentally specific mobility disability. Their approach involves self-reports of frequency of encounter and avoidance of 24 features of the physical environment, grouped into eight dimensions: distance, temporal, ambient, terrain, load, postural transitions, attention, and density. Initial evaluations of validity and reliability with a small sample suggest that the approach appears promising (Shumway-Cook et al. 2005).

WORKSHOP RATIONALE AND GOALS

Advances in conceptual thinking since the development of ADL and IADL items provide new opportunities to expand the range of questions that might be answered with survey data. Standardization of disability measures, for example, may promote comparisons across surveys, groups, and countries. Distinguishing physiological, environmental, and social components of disability, for example, may help policy makers better target resources at interventions likely to have high impact on population disability rates. Moreover, such distinction can help researchers track and understand shifts in population-level disability trends. Widespread use of these new measures could also improve our understanding at the individual level of the physiology of functional loss and recovery, the accommodation process, and the effectiveness of interventions to enhance independence and participation. Many of the advances discussed here are quite recent and have not been routinely incorporated into most national surveys that address late-life disability.

The workshop on Improving Survey Measures of Late-Life Disability will review advances in our understanding and measurement of late-life disability with the aim of answering two fundamental questions:

• Are our current measures of late-life disability meeting the needs of researchers and policy makers?
• How can we improve measures of late-life disability within current surveys?

The meeting will involve three sessions. The first session will be a panel discussion to flesh out the opportunities that new measures of disability might provide to policy makers and researchers. The second session will include six speakers, each focusing on an innovation in disability measurement. Presentations will address efforts to standardize measures and underlying components of disability (physical functioning; the environment and assistive technology; and time use and participation). The final session will involve a panel discussion about the practical considerations in implementing new measurement techniques with the aim of identifying the most promising strategies. The complete workshop agenda and biographies of participants are included in the Appendix.

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World Health Organization. International Classification of Functioning and Disability. Geneva, Switzerland: World Health Organization; 1999.

APPENDIX A: Additional Tables

APPENDIX B: Workshop Agenda

APPENDIX C: Biographies of Workshop Participants and Organizers

Workshop on Improving Survey Measures of Late-Life Disability Funded by
Office of the Assistant Secretary for Planning and Evaluation
BIOGRAPHIES OF WORKSHOP PARTICIPANTS AND ORGANIZERS

Emily Agree, Ph.D. (Johns Hopkins University)
Dr. Emily Agree is an Associate Professor in both the Population and Health Sciences and Sociology departments at Johns Hopkins University. She is currently involved in research on the social consequences of chronic illness among older persons in the United States. Dr. Agree has studied the role of assistive technology in long-term care among older persons in the United States, including how older disabled persons choose technology and/or personal care to meet their long-term care needs and the effectiveness of technology and personal care arrangements in alleviating disability, relieving the burden on informal caregivers, and reducing health care costs. She is currently collaborating on a project to develop and evaluate measures of assistive technology and the environment.

Susan Allen, Ph.D. (Brown University)
Dr. Allen is an Associate Professor in the Departments of Community Health and Sociology at Brown University. She is also Acting Director of the Center for Gerontology and Health Care Research at Brown. Dr Allen has a long history of studying home care issues among people with chronic conditions and impairments. Her research has focused on both formal and family home care, and on the implications of unmet need for help at home for the quality of life and patterns of service use among people with disability who live in the community. Recently Dr. Allen has extended her interest in home supports from formal and informal human assistance to technological assistance. Dr. Allen has served as Principal Investigator on grants funded by the National Institute on Aging, the National Cancer Institute, the Robert Wood Johnson Foundation and the Milbank Memorial Fund.

Janet Fast, Ph.D. (University of Alberta)
Dr. Fast researches family and consumer policy issues. A major theme is the paid and unpaid work of family members. She currently co-leads a large international, multidisciplinary team investigating the juxtaposition of costs and contributions of adults with chronic illness and disability. On the cost side, the team is examining the consequences of recent health and social policy reform for family and friends who care for frail seniors or other adults with chronic illness and disability. On the contributions side, they are exploring the productive activities of older adults and adults with chronic illness and disability. Dr. Fast also conducts research on workplace policy as it relates to family members' ability to balance paid work and family demands.

Vicki A. Freedman, Ph.D. (Polisher Research Institute)
Dr. Freedman is a Senior Research Scientist and at Polisher Research Institute, a private, non-profit gerontological research organization affiliated with the Abramson Center for Jewish Life (formerly, Philadelphia Geriatric Center). From 2002-2005 she served as the Institute's director. Dr. Freedman has published extensively on the topics of population aging, disability, and long-term care, including several widely publicized articles on trends in late-life functioning. Her current portfolio of research projects focuses on disparities and causes of late-life health trends; policy interventions to promote late-life disability decline; the development of measures of assistive technology use and the home environment; barriers to the use of technology in residential long-term care settings, and the role of neighborhoods in late-life health.

Thomas Gill, M.D. (Yale University)
Dr. Gill is Associate Professor of Medicine with Tenure at the Yale University School of Medicine. He is a graduate of the Pritzker School of Medicine at the University of Chicago, and he completed his residency training in internal medicine at the University of Washington. Dr. Gill received his research training in clinical epidemiology as a Robert Wood Johnson Clinical Scholar at Yale, and he joined the Yale faculty in 1994 after completing an additional year as a geriatrics fellow. Dr. Gill is a leading authority on the epidemiology and prevention of disability and functional decline among older persons. His findings have been published in high impact biomedical and epidemiology journals, including the New England Journal of Medicine, JAMA, Annals of Internal Medicine, and American Journal of Epidemiology. Dr. Gill is the recipient of numerous awards, including the 2001 Outstanding Scientific Achievement for Clinical Investigation Award from the American Geriatrics Society. In April 2005, he was elected to the American Society of Clinical Investigation (ASCI), one of the nation's oldest and most respected medical honor societies. Dr. Gill's research and mentoring program in disability and disabling disorders is currently supported by an NIA Midcareer Investigator Award in Patient-Oriented Research (K24) and two NIA-funded R01s.

Howard Iams, Ph.D. (SSA)
Dr. Iams is the Director of the Division of Policy Evaluation in the Social Security Administration’s research office. Since coming to SSA in 1978, Dr. Iams has worked on a variety of research and evaluation activities. He worked on evaluation demonstrations in the AFDC program specializing in the subjects of performance measurement and work demonstrations. Using the 1982 New Beneficiary Survey data system, he conducted analyses of mortality and of employment patterns of newly disabled and retired beneficiaries. Dr. Iams also managed the 1991 re-interviews to the New Beneficiary Survey. Since 1986 he Iams has been conducting policy evaluations with survey data from the Census Bureau’s Survey of Income and Program Participation (SIPP) matched to SSA administrative records of earnings and benefits. In collaboration with Steve Sandell, he designed and developed the Modeling Income in the Near Term (MINT) data system with matched SIPP data. SSA uses MINT to estimate the distributional impact of Social Security reform proposals and to project the baby boom and other future retirees in the 21st Century.

Lisa Iezzoni, M.D., M.Sc. (Harvard University)
Lisa I. Iezzoni is Professor of Medicine at Harvard Medical School and Co-Director of Research in the Division of General Medicine and Primary Care, Department of Medicine, at Beth Israel Deaconess Medical Center in Boston. She received her degrees in medicine and health policy and management from Harvard University. Dr. Iezzoni has conducted numerous studies for the Agency for Healthcare Research and Quality, the Medicare agency, and private foundations on a variety of topics, including evaluating methods for predicting costs, clinical outcomes, and substandard quality of care. She has published and spoken widely on risk adjustment and has edited a textbook, now in its third edition (2003), on risk adjustment for measuring health care outcomes. A 1996 recipient of the Investigator Award in Health Policy Research from The Robert Wood Johnson Foundation, she is studying health policy issues relating to persons with disabilities. Dr. Iezzoni is a member of the Institute of Medicine in the National Academy of Sciences, serves on the editorial boards of major medical and health services research journals, and is on the Board of Directors of the National Quality Forum. Her book When Walking Fails was published in the spring 2003.

Jennifer Madans, Ph.D. (CDC/NCHS)
Dr. Madans has been the Associate Director for Science, National Center for Health Statistics, since May 1996 and is responsible for the overall plan and development of NCHS's data collection and analysis programs. Since Dr. Madans joined the Center, she has concentrated her research efforts on data collection methodology, aging, health services research and chronic disease epidemiology. She has directed two national longitudinal studies (NHANES I Epidemiologic Followup Study and the National Nursing Home Followup Study) as well as the redesign of the National Health Interview Survey questionnaire. She was one of the designers of the DHHS Survey Integration Plan and of the State and Local Area Integrated Telephone System. Dr. Madans is a Fellow of the American Statistical Association.

Ken Manton, Ph.D. (Duke University)
Dr. Manton is Scientific Director of the Center for Demographic Studies at Duke University and a Research Professor in Duke’s Department of Sociology, as well as a Medical Research Professor in the Department of Community and Family Medicine at the Duke University Medical Center. He is currently Principal Investigator on a number of grants and cooperative agreements, among them the National Long Term Care Survey and a program project grant focusing on health forecasting and Medicare utilization funded by NIA. Dr. Manton’s primary expertise is in the areas of mathematically sophisticated analytic procedures and biologically-based population level models of health and mortality, particularly of aged populations. He has published over four hundred monographs and articles and received in 2000 the first M. Irene Ferrer Award for Outstanding Original Research in Gender-Specific Medicine from The Partnership for Women's Health at Columbia University. He was the 1990 recipient of the Mindel C. Sheps Award in Mathematical Demography and Demographic Methodology.

DEB Potter, M.S. (AHRQ)
Ms. Potter is Senior Survey Statistician at the Agency for Healthcare Research and Quality. She has a wide range of experience in the design and collection of government health and long-term care surveys. She is project manager for the Medical Expenditure Panel Survey (MEPS) Nursing Home Component (NHC). She is co-leader of AHRQ's Long-Term Care Research and Data Development Group. Her research interests include the design and implementation of an integrated data system to support long-term care health services research for the Department of Health and Human Services (HHS).

Robert Schoeni, Ph.D. (University of Michigan)
Dr. Schoeni is Associate Research Professor at the Institute for Social Research and Associate Professor of Economics and Public Policy at the University of Michigan. He studies labor economics, the family, aging, and welfare policy. Recent studies include the investigation of changes in old-age health status and disability, the effects of welfare reform on various outcomes, the economic consequences of workplace injuries, and poverty among older women. Dr. Schoeni also serves as Associate Director of the Panel Study of Income Dynamics.

Anne Shumway-Cook (University of Washington)
Dr. Shumway-Cook is an Associate Professor and Physical Therapist in the Department of Rehabilitation Medicine at the University of Washington. Her research interests include mechanisms underlying imbalance in the aging adult and clinical methods for assessing and treating imbalance. She has recently published several articles on the role of environmental demands and community mobility in older adults.

James P. Smith, Ph.D. (RAND Corporation)
Dr. Smith holds the RAND Chair in Labor Markets and Demographic Studies and was the Director of RAND's Labor and Population Studies Program from 1977-1994. He has led numerous projects, including studies of immigration, the economics of aging, black-white wages and employment, wealth accumulation and savings behavior, and the interrelation of health and economic status. He is currently a co-Principal Investigator for The New Immigrant Survey. Dr. Smith was the Chair of the Panel on Demographic and Economic Impacts of Immigration (1995-1997), for the National Academy of Sciences. The Panel was convened to examine the interconnections of immigration, population, and the economy, and to provide evidence about the impact of immigration. Dr. Smith has served on the Population Research Committee at the National Institutes of Health. He currently serves on the NIA Data Monitoring Committee for the Health and Retirement Survey (HRS) and was chair of the National Science Foundation Advisory Committee for the Panel Study of Income Dynamics. Dr. Smith was the public representative appointed by the Governor on the California OSHA Board. He has received the National Institutes of Health MERIT Award, the most distinguished honor NIH grants to a researcher.

Brenda Spillman, Ph.D. (Urban Institute)
Dr. Spillman, a health economist, joined the Urban Institute as a Senior Research Associate in August 1998. Before that she was a research fellow at the Agency for Health Care Policy and Research (now AHRQ) for 11 years. In recent years she has specialized in research on disability and long term care use and financing, including nursing home use and financing, home care, long term care insurance and public financing, informal caregiving, and projections of service use and cost for the Medicare elderly. Dr. Spillman’s earlier work focused on the nonelderly uninsured, Medicaid, Medicare, and the impact of financing on health care utilization. In addition to continuing work on long term care and disability-related projects, Dr. Spillman’s current work deals with access and utilization of services by low-income adults, as part of the Assessing the New Federalism Project. Dr. Spillman has worked with a broad range of complex national surveys, Medicare, and Medicaid data and has experience in the design of questionnaires and analytic oversight of editing and imputation through her work on the Medical Expenditure Panel Survey.

Timothy Waidmann, Ph.D. (Urban Institute)
Dr. Waidmann is an economist with post-doctoral training in the demography of aging. He has worked on a series of projects dealing with the measurement of disability in surveys. Much of his research studies the potential for policy and economic factors to contaminate self-reported health and disability measures in surveys. In the areas of aging, disability and long-term care, Waidmann has designed and conducted studies of disability trends among the elderly in the U.S. and other industrialized countries; the impact of these trends on Medicare spending; the impact of potential reforms in the Medicare program; access to physician services among Medicare beneficiaries; and models of residential transition among the elderly. In the area of work-disability, Waidmann has worked on several studies of the impacts of health and government disability policy on labor force decisions using the Health and Retirement Survey, and a study of the social welfare implications of imperfect medical screening in the Social Security disability insurance program.

Julie Weeks, Ph.D. (CDC/NCHS)
Dr. Weeks has been employed at the National Center for Health Statistics since 1989, and is currently with the Office of Analysis and Epidemiology. Since she came to NCHS, she has worked on the Longitudinal Studies of Aging (LSOAs), and is currently the Project Director. Her research interests include the demography of aging, including health status and social support among the elderly, and survey methodology. She currently serves a committee member of the Interagency Forum on Aging-Related Statistics & Interagency Household Survey Nonresponse Group.

David R. Weir, Ph.D. (University of Michigan)
Dr. Weir is Associate Director of the Health and Retirement Study. His current research interests include the measurement of health-related quality of life; the use of cost-effectiveness measures in health policy and medical decision-making; the role of supplemental health insurance in the Medicare population; the effects of health, gender, and marital status on economic well-being in retirement; and the effects of early-life experience on longevity and health at older ages.