Gerontological nurses could recite them while sleeping: bathing, dressing, toileting, transferring, continence, and feeding. These traditional activities of daily living (ADL) commonly are used by nurses to assess the functional abilities of elderly patients, to determine a patient's need for assistive devices or help from caregivers, or to recommend placement in an appropriate setting or service arrangement. Accurate measurement of function is particularly important for elderly patients with multiple interrelated problems whose ability to function cannot be predicted simply from a medical diagnosis.
Can nurses accurately measure functional status only by asking the patient or a family member for a report of ability to perform the six ADL? Clearly, nurses' accurate measurement of functional disability is important to each elderly patient because the results of such tests may be used to change many aspects of the patient's way of living. Therefore, it is vital that gerontological nurses not just accept the traditional protocol for such measurements but stay abreast of current research in the measurement and prediction of functional disability in older adults. The purpose of this article is to discuss the weaknesses of the traditional self-report of ADL as a sole measure of functional status and to suggest the use of research-based performance tests to augment the ADL reports, especially for older adults who deny difficulty with ADL tasks.
HISTORICAL DEVELOPMENT OF ACTIVITIES OF DAILY LIVING
It has been more than 30 years since the development of the Index of ADL (Katz, Ford, Moskowitz, Jackson, & Jaffe, 1963), yet it remains a standard assessment tool of general functional disability in older adults. It was developed for use with acutely ill patients in hospitals and was designed to be a rating instrument used by clinicians. The index assesses independence in six activities: bathing, dressing, toileting, transferring from bed to chair, continence, and feeding. The original scoring was a 3 -point scale for each activity, rated by a clinician. Each score then was dichotomized to independent or dependent according to a guideline for each activity. The resulting scores were summarized into one of eight disability categories.
The Index of ADL, a unique idea at the time of its introduction, seems to have been accepted by acclaim, rather than by formal reliability or validity testing (McDowell & Newell, 1996). For example, estimates of test-retest reliability have not been reported, though the Index of ADL often is used as a measure of change over time, implying that the index is a reliable measure. The Index of ADL has been accepted so widely, with little reliability or validity data to support its use, that content validity may be inferred from its popularity among clinicians and researchers. However, criterion and construct validity have seldom been addressed in studies.
Although other scales of tasks of daily living have been developed, such as the Barthel Index (Mahoney & Barthel, 1965), Rosow-Breslau Functional Health Scale (Rosow & Breslau, 1966), several indexes of Instrumental Activities of Daily Living (IADL) (e.g., Lawton & Brody, 1969), and many disease-specific activity scales, the basic ADL index developed by Katz et al. in 1963 is the most common measure of functional disability used in gerontological nursing practice and research.
ARE ADL APPROPRIATE MEASURES OF FUNCTIONAL DISABILITY?
The ubiquitous use of the Index of ADL in clinical settings and research studies does not preclude the need for discussion regarding its appropriateness in assessing older adults. There are several problems which should be considered: scoring, self-report, changes in format, and use in diverse populations.
Although the original Index of ADL had a 3-point scale for rating each task and a final score that contained eight categories of disability, it currently is common to find that researchers and clinicians have simplified the scoring. Often, a cut-off is established below which individuals are rated as dependent. This dichotomization of scores eliminates much of the variability of the data and has no psychometric support in the literature. Further, many researchers use different thresholds for dichotomization, making it difficult to compare the results of different studies.
In addition to differences in scoring methods, some research and clinical settings have changed the ADL tasks, either adding new tasks or deleting one or more of the orìgìnaì six ADL. Again, this causes difficulty in comparing research studies, as well as misinterpretations in rating patients, for example, as they move from an ambulatory clinic to a home care protocol, where a change in functional status may reflect a change in the list of tasks rather than a change in actual functional disability.
Finch, Kane, and Philp (1995) cite two more problems with the scoring of ADL. First, to define an individual as dependent in a task (so the dependencies can be summed to a final score), one must first establish a threshold. If the line is drawn at a high level of dependency (e.g., totally dependent on someone else), patients with more modest levels of disability will not be recognized at all. Conversely, if the threshold is low, there will be no differentiation among severe levels of disability. Second, a simple summing of the task scores implies that every task has the same importance, although clinical judgment suggests some tasks contribute more to dependency than others.
To improve on the traditional scoring, Finch et al. (1995) developed a weighted scale of tasks that incorporated all the original ADL and some more difficult tasks, such as shopping and housecleaning. Although untried in clinical practice, this refinement of the traditional ADL tool may be useful to nurses because individual items can be rearranged or omitted because the weight assigned to each component is self-contained. If this scale proves valid in further studies, this flexibility and the weighted scoring may be a significant improvement from the traditional ADL scale.
The original Index of ADL was tested on patients in hospitals, where clinicians rated patients' ability to perform the six tasks. However, it currently is common to use the index as a measure of functional status in older adults who are not hospitalized, such as those who live in the community and in long-term care facilities. In addition, the mdex often is used as a self-report instrument, a method that has been challenged by several researchers. For example, Fried et al. (1996) found that older adults in an early stage of disability did not accurately answer the "yes" or "no" format of the questions, because they did not perceive their own disabilities, presumably because physical changes had been gradual, adaptation had occurred, and patients did not recognize the decline in function.
Another problem with self-report is that some older adults may interpret the meanings of the ADL questions differently than the meanings intended by the interviewers. For example, in one study, elderly respondents were asked about the need for "help from another person" to perform each activity. Before conducting the study, the researchers had decided that use of a special seat in the shower did not constitute receiving help to perform the bathing task. However, many respondents considered this help from another individual, even although no one actually was present to help them. They thought someone had helped them by inventing the device, telling them about it, selling it to them, or installing it (Keller, Kovar, Jobe, & Branch, 1993).
These discrepancies in meanings attributed to the ADL questions are crucial to assessing the reliability and validity of self-reports of functional disability in clinical practice. Usually, nurses ask patients to answer "yes" or "no" to the question of whether help is needed on each task in a list of ADL. Moreover, in many protocols the sum of these answers again is dichotomized: Patients are classified as functionally dependent or independent. Clearly, a misinterpretation or lack of recall on one or two questions could skew the results of an assessment that uses self-report of ADL tasks as its sole measure.
Changes in Format
An additional problem is caused by the numerous adaptations of the Index of ADL, many of which phrase the questions differently. For example, a study examining 1 1 large national databases which used ADL questions as measures showed there was variation in the way surveys asked subjects about ADL functioning by (Wiener, Hanley, Clark, & Van Nostrand, 1990):
* Level of difficulty.
* Type of assistance needed.
* Duration of problem.
The authors suggested these discrepancies may account for statistical differences across surveys. For example, the National Medical Expenditure Survey in 1987 estimated there are 60% more elderly people with ADL problems than reported by the National Health Interview Survey Supplement on Aging in 1984 (Wiener et al., 1990). These are large databases (N = 5,750 and N = 16,148, respectively) of the type often used to formulate public policy. Therefore, in addition to causing differences among research studies and clinical ratings, the various methods of asking the ADL questions can have an impact on national budget and health issues.
Use in Diverse Populations
The Index of ADL recently has been used to compare Blacks, Hispanics, and Whites on risk factors (Camacho, Strawbridge, Cohen, & Kaplan, 1993), trends in institutionalization (Clark, 1997), levels of disability (Miller et al., 1996), and health status (Stump, Clark, Johnson, & Wolinsky, 1997). However, none of these studies included psychometric analyses of the Index of ADL in separate ethnic groups to establish reliability and validity in those populations. As the inclusion of different ethnic groups in studies becomes more common, perhaps validity will be established separately for diverse populations. Currently, the Index of ADL is used clinically with the assumption of validity in all racial and ethnic groups.
At the level of the individual patient, gerontological nurses should recognize that ADL scores are "soft" measures at best because selfreport of functional disability is subject to variation for many reasons including the wording of questions, interpretation of meanings by the subjects, and personal reasons for overreporting or underreporting disability. Therefore, the ADL questions, although useful, should be used along with other measures and clinical judgment. Moreover, extreme caution should be used if ADL scores of disability are the primary measure used in justifying a major change for a patient, such as a move to a long-term care facility.
ARE PHYSICAL PERFORMANCE TESTS MORE USEFUL THAN ADL?
Older adults' selfreports of performance of ADL may be inaccurate because of misinterpretation of the questions, failure to recognize gradual changes in performance, or differences in the ways researchers present the questions. Therefore, the addition of performance tests to ADL self-reports may provide a better measurement of functional disability than ADL scores alone. In particular, some studies have shown that tests of lower extremity strength are related to deficiencies in ADL performance, and lower extremity performance tests may predict future functional disability.
Several studies have found moderate correlations between patients' s elf- reports of ability to perform tasks and their actual performance of the same tasks. When there was a difference, the self-reported disability was higher than the actual physical limitation (Kelly-Hayes, Jette, Wolf, D'Agostino & Odell, 1992; Reuben, Valle, Hays, & Siu, 1995). However, observing performance of all six ADL tasks is too time consuming in clinical nursing practice. Therefore, studies using simple performance tasks to measure functional disability may be more useful.
For example, a metaanalysis of data from the Frailty and Injury: Cooperative Studies of Intervention Trials (FICSIT) compared physical performance tests with self-reported dependencies in eight IADL tasks (Judge, Schechtman, Cress, & the FICSIT group, 1996). The researchers used self-reported dependencies in eight IADL as the dependent variable, rather than dependency in ADL, because they believed there was a hierarchical relationship between the two scales (i.e., IADL deficits precede those in ADL). After adjustment for covariates, the association between IADL dependencies and hand grip strength was significant at only two sites. However, the test of balance was significantly associated with IADL dependencies at four of the six sites, and gait speed was significant at five sites. Although these data are cross - sectional and, therefore, are not predictive, there is a relatively stronger association between IADL dependencies and the tests of lower extremity performance (gait and balance) when compared to the association of IADL dependencies and the upper extremity test (grip strength) (Judge et al., 1996).
Similarly, a study that compared self-report (self-perceived health using the Sickness Impact Profile [Bergner, Bobbin, Carter, & Gilson, 1981]) and four different physical performance tests (i.e., gait speed, chair-stand time, grip strength, balance), found that only gait speed was independently associated with selfperceived functional disability, leading the authors to suggest this test as a simple clinical measure for assessing function (Cress et al., 1995).
In another study, researchers analyzed the results of 5,174 home interviews with elderly subjects in the Established Populations for the Epidemiologic Study of the Elderly (EPESE) to investigate the association between self-report of disability and performance-based measures of lower extremity functioning (Guralnik et al., 1994). The performance tests - standing balance, walking speed, and chair-rise time - were selected from previous research with the consideration that the assessments could be administered by a single lay interviewer in a home setting with limited unobstructed space. Interviewers were trained by videotape to ensure uniformity of administration of the tests, which together required from 10 to 15 minutes to administer. Scores were ordinal and were summed for a final performance score (Guralnik et al., 1994).
Results showed that the three performance test scores were significantly correlated with each other, and multiple regression analysis showed that self-report of functional dependency on ADL tasks explained 42% of the variance in the summary performance scores. Further, there is evidence in these data that performance measures may contribute more information than that supplied by selfreport of disability. When subjects were divided into three subgroups based on their self -reports oí ìeveì oí disability in ADL, there were systematic differences in their scores on the performance tests within each group. This may indicate that the performance tests were providing information not obtainable from self-report. In the discussion, Guralnik et al. (1994) acknowledged the need for further methodological work on the use of physical performance tests in standard gerontological assessment and suggested self-reports of disability may be adequate for many research and clinical situations.
However, the possibility of uncovering limits in physical performance, especially in a high-performing segment of the population reporting no ADL disabilities, may warrant the introduction of performance tests into a gerontological nursing assessment. The study by Guralnik et al. (1994) may be useful in this respect because the tests were chosen to be simple, quick, and practical for administration in a small space with no special equipment - important factors to nurses.
CAN PHYSICAL PERFORMANCE TESTS PREDICT FUTURE FUNCTIONAL DISABILITY?
Although correlations between scores on performance tests and selfreports of functional disability were demonstrated in the above studies, causality cannot be assumed. However, longitudinal analysis of the EPESE data by researchers showed that functional disability 4 years later was predicted by performance on three physical tests: standing balance, timed walk, and chair rise-and-sits. The cohort study included 1,122 men and women age 71 or older who were living in the community in 1988. All subjects reported no difficulty with ADL and were tested in the three performance tests. Four years later, they again were interviewed for a self -report of ADL and were tested in the same three performance tasks (Guralnik, Ferrucci, Simonsick, Salive, & Wallace, 1995).
The results showed that scores on the three performance tests at baseline predicted functional disability (defined as inability to perform one or more ADL) 4 years later. The independent influence of each of the three physical tests on functional disability remained when age, gender, and chronic illness were held constant. Guralnik et al. (1995) concluded that lower extremity function may be particularly predictive because it reflects physiologic decline, the effects of chronic disease, and coexisting conditions that have not yet caused frank disability. The results of this study may establish a predictive link between lower extremity physical performance and later functional disability, even if there are no clinical indicators of decline in performance of ADL at baseline.
CLINICAL NURSING PRACTICE IMPLICATIONS
The proportion of older adults in the American population continues to grow. Moreover, most elderly patients who report some difficulty with everyday tasks live in the community rather than in institutions (Fulton, Katz, & Jack, 1989). Therefore, functional assessment measuring tools used by nurses must be appropriate for home and clinic settings. For gerontological nurses, accurate functional assessment can serve several purposes including the measurement of outcomes, the design of interventions, and most important, the prediction and prevention of functional disability.
Functional disability commonly is measured with questions about ADL, although many researchers have cited problems with this method of measurement. For example, Finch et al. (1995) found that the tasks were not all of equal difficulty although each task is weighted equally in the traditional summing of a disability score. In addition, researchers have found that the task questions are asked differently by different instruments. Some questionnaires ask if patients can perform each task and some ask if patients need assistance with each task (Wiener et al., 1990). This makes it difficult to compare the meaning of scores in different studies. Not only are the questions about ADL sometimes phrased differently, patients either may misinterpret the meanings of the questions (Keller et al., 1993) or may answer inaccurately because they do not recognize their own adaptations to disability (Fried et al., 1996).
This review of the research literature has raised questions regarding the utility of the traditional selfreport of ADL used by many gerontological nurses for functional disability assessment. Although research has introduced new methods, such as weighted scales, more studies are needed to test the validity and reliability of these new methods, especially when they are used in clinical settings. Until more studies are completed using improved scales, nurses may incorporate new ideas into their practices in individual ways, such as adding performance testing to ADL questions.
For example, when patients report little or no difficulty with ADL tasks, nurses may introduce performance tests designed to discover physical limitations leading to future functional disability. With the use of performance tests, preclinical disability or limitations that are likely to lead to disability may be found early and disability may be prevented by early intervention. Simple performance tests also may be useful when nurses doubt the accuracy of ADL self-report, such as when patients are unable or unwilling to answer ADL questions. In fact, if the performance tests are easy to administer, some nurses may choose to routinely add them to all ADL assessments.
Many researchers have found that tests of lower extremity function are associated with functional disability (Cress et al., 1995; Guralnik et al., 1994, 1995; Judge et al., 1996). Moreover, Guralnik et al. (1995) found that three particular lower extremity physical tests predicted functional disability in ADL tasks 4 years later. Balance, gait, strength, and endurance were evaluated by these three simple tests: ability to stand with the feet together in the side-by-side, semi-tandem, and tandem positions; time to walk 8 feet; and time to rise from a chair and return to the seated position five times. Guralnik et al. (1994) found that these tests could be administered in limited space in the home, required only 10 to 15 minutes, and caused no injuries when administered to 5,174 individuals. The protocol for these three physical performance tests is provided in the Appendix on page 24 of this article.
There is general agreement that as individuals age, their ability to perform self-care tasks, or ADL, may decrease. The assessment of functional status to determine the degree of functional disability is a key concept in gerontological nursing because early recognition of functional difficulty with timely intervention may impact greatly the quality of life of elderly patients. Although traditional measurement of functional disability such as selfreport of ADL may be adequate in many situations, the addition of performance tests may provide vital information about some patients.
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