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 persons 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 patients 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 applicants 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].
|TABLE 1. Measures of Activities of Daily Living in Selected Nursing Surveys|
|Survey||ADL Items||IADL Items|
|Difficulty||Help||Equipment||Number of ADLs Mentioned||Difficulty||Help||Number of IADLs Mentioned|
|American Community Survey (ACS); 1999 and later||X||3||X9||2|
|Health and Retirement Study (HRS); 1995 and later||X||X (if difficulty)||X7||6||X10||X (if difficulty)||7|
|Medicare Current Beneficiary Survey (MCBS); 1992 and later (Community sample)||X1||X (if difficulty)3||X (if difficulty)||6||X11||X (if difficulty)||6|
|Medical Expenditure Panel Survey (MEPS-Long Term Care Supplement); 1997 and later||X3,4||X8||5||X3,12||7|
|National Health and Nutrition Examination Survey (NHANES); 1999-2000||X1||X8||5||X9||3|
|National Health Interview Survey (NHIS); 1997 and later||X5||X8||6||X5,9||4|
|National Long Term Care Survey (NLTCS); 1982 and later (Community sample)|
|Survey of Income and Program Participation (SIPP); 1991 and later||X16||X (if difficulty)5||X8||8||X15||X (if difficulty)5||4|
|Supplement on Aging (SOA); 1995||X1||X||X||7||X11||X||8|