Revised Direct Assessment of Functional Status for Independent Older Adults
Revised Direct Assessment of Functional Status for Independent Older Adults
Purpose: The original version of the Direct Assessment of Functional Status (DAFS), a measure of instrumental activities of daily living (IADLs), was found to have a ceiling effect in older adults living independently in the community. This suggested that the tasks measured, although relevant, do not require full use of this population's abilities, and thus, the instrument may not be sensitive to the early decrements in IADLs that can signal initial cognitive impairment and may not detect improvements in IADLs over time, which is especially important in intervention research.
Design and Methods: By removing items with little to no variation and adding more difficult subscales that emphasized medication management skills, we designed the DAFS-Extended (Direct Assessment of Functional Status-Revised [DAFS-R]) to be more challenging for elders living independently.
Results: Analysis with a sample of 45 older adults suggested that scores on the DAFS-R appear to be more normally distributed than on the original version. The DAFS was able to differentiate individuals with varying standard profile scores on the Rivermead Behavioural Memory Test memory performance instrument (normal, poor, and impaired). In addition, the reliability and validity of the DAFS-R were supported in this sample.
Implications: Given the large number of older adults who regularly take multiple prescription medications, deficits in medication management skills can have serious consequences. A performance measure that emphasizes these higher level daily living skills can help providers screen for initial signs of functional decline.
Successful performance of instrumental activities of daily living (IADLs) such as taking medications, managing money, and using a telephone requires intact executive function to sequence tasks, make appropriate judgments, and organize abilities (Bell-McGinty, Podell, Franzen, Baird, & Williams, 2002; Bertrand, Willis, & Sayer, 2001; Burton, Strauss, Hultsch, & Hunter, 2006; Dodge, Du, Saxton, & Ganguli, 2006; Insel, Morrow, Brewer, & Figueredo, 2006). In addition to executive function, physical disabilities, sensory impairment, medical conditions, emotional status, and perceived health status are also important predictors of functional capacity (Cahn-Weiner, Malloy, Boyle, Marran, & Salloway, 2000; Marcopulos, McLain, & Guiliano, 1997). Early measures of instrumental activities were self-reported; however, with concerns about the accuracy of these self-reports, actual observation of performance has increased (Diehl, Marsiske, Horgas, & Saczynski, 1998; Diehl, Willis, & Schaie, 1995; Lawton, 1988; Lawton & Brody, 1969).
Managing medications is an important daily task for older adults. In fact, 90% of adults aged 65 years and older take at least 1 prescription medication per week, 40% take at least 5 different medications, and 12% are taking more than 10 types of medications per week (Gurwitz et al., 2003; Zhan et al., 2001). Several available measures of IADL include medication management; however, many are self-report and require only recall (Diehl et al., 1998; Mahurin, DeBettignies, & Pirozzolo, 1991). For example, in the Physical Functioning Inventory, participants are asked how they would obtain medication and whether they have any difficulty taking them (Whetstone et al., 2001), and the timed IADL test requires participants to correctly identify and read the label on a medication bottle in a limited time (Edwards et al., 2005). Assessment of medication skills is limited on most performance measures; however, a measure is needed that more clearly reflects the skills required to manage multiple medications.
The Direct Assessment of Functional Status (DAFS; Loewenstein et al., 1989) has been used to assess the functional status of older adults and their ability to successfully complete IADLs. The 85-item DAFS measures participants' time orientation, communication abilities, transportation knowledge, financial skills, shopping skills, eating skills, and dressing/grooming skills and is administered in outpatient settings. The DAFS has been shown to have high interrater and test–rest reliability among patients identified as possibly having memory disorders and among normal controls. Validity was supported by the significant differences in scores between patients diagnosed with Alzheimer's disease and individuals without cognitive impairment (CI). In addition, DAFS scores were negatively related to scores on the Blessed Dementia Rating Scale among 30 patients with memory impairment. A modified version of the DAFS tested with community elders has been found sensitive to level of cognitive function and dementia (Rankin & Keefover, 1998).
In our SeniorWISE study (McDougall et al., in press) with 265 independent older adults who were screened out for dementia, we found that the DAFS (even excluding the eating and dressing/grooming skills subscales) had a nonnormal distribution on the first administration before intervention or opportunity to practice completing the instrument and also showed a ceiling effect. We used the modified version to take into account the lack of kitchen and bathroom facilities in the evaluation rooms at study sites. The domains measured from the DAFS in this study were time orientation, communication abilities, transportation, financial skills, and shopping skills. A fifth domain, medication skills, was added for the study. Medication skills with three sections (identifying, refilling, and managing medications) was added to more fully capture cognitive tasks that are important for living independently in older age (Table 1 shows the mean, minimum, and maximum scores when administered at baseline in the SeniorWISE study). That is, scores on the DAFS were skewed to the upper end of the distribution (see Figure 1). Furthermore, item analysis of the DAFS showed that many of the items had little to no variation, and participants scored very high despite the fact that two thirds scored in the poor or impaired ranges on the Rivermead test of everyday memory performance (Wilson, Cockburn, & Baddeley, 1991). This pattern of results suggested that the DAFS might not be sensitive to the early deficits in functioning exhibited by older adults experiencing poor memory performance but are still living independently in the community.
(Enlarge Image)
Figure 1.
Frequency histogram of scores on the 85-item Direct Assessment of Functional Status (DAFS) at Time 1 of the SeniorWISE study for the 45 individuals in the present study.
We concluded that a more challenging assessment was needed to test the upper limit of the older adults' skills and detect initial deficits in IADLs that might signal the need for more extensive testing of cognitive function. Also, because correct use of medications is so important for remaining independent, we decided that medication management skills should receive greater emphasis. Consequently, we modified the DAFS and tested the modified version with a subset of SeniorWISE participants approximately 2 years after they completed the study. We revised the instrument with the approval of Dr. David Lowenstein and then examined the psychometric properties of the Direct Assessment of Functional Status-Revised (DAFS-R). This article describes our revision of the DAFS and presents our initial findings on the score distribution, reliability, and validity of the new instrument.
Abstract and Introduction
Abstract
Purpose: The original version of the Direct Assessment of Functional Status (DAFS), a measure of instrumental activities of daily living (IADLs), was found to have a ceiling effect in older adults living independently in the community. This suggested that the tasks measured, although relevant, do not require full use of this population's abilities, and thus, the instrument may not be sensitive to the early decrements in IADLs that can signal initial cognitive impairment and may not detect improvements in IADLs over time, which is especially important in intervention research.
Design and Methods: By removing items with little to no variation and adding more difficult subscales that emphasized medication management skills, we designed the DAFS-Extended (Direct Assessment of Functional Status-Revised [DAFS-R]) to be more challenging for elders living independently.
Results: Analysis with a sample of 45 older adults suggested that scores on the DAFS-R appear to be more normally distributed than on the original version. The DAFS was able to differentiate individuals with varying standard profile scores on the Rivermead Behavioural Memory Test memory performance instrument (normal, poor, and impaired). In addition, the reliability and validity of the DAFS-R were supported in this sample.
Implications: Given the large number of older adults who regularly take multiple prescription medications, deficits in medication management skills can have serious consequences. A performance measure that emphasizes these higher level daily living skills can help providers screen for initial signs of functional decline.
Introduction
Successful performance of instrumental activities of daily living (IADLs) such as taking medications, managing money, and using a telephone requires intact executive function to sequence tasks, make appropriate judgments, and organize abilities (Bell-McGinty, Podell, Franzen, Baird, & Williams, 2002; Bertrand, Willis, & Sayer, 2001; Burton, Strauss, Hultsch, & Hunter, 2006; Dodge, Du, Saxton, & Ganguli, 2006; Insel, Morrow, Brewer, & Figueredo, 2006). In addition to executive function, physical disabilities, sensory impairment, medical conditions, emotional status, and perceived health status are also important predictors of functional capacity (Cahn-Weiner, Malloy, Boyle, Marran, & Salloway, 2000; Marcopulos, McLain, & Guiliano, 1997). Early measures of instrumental activities were self-reported; however, with concerns about the accuracy of these self-reports, actual observation of performance has increased (Diehl, Marsiske, Horgas, & Saczynski, 1998; Diehl, Willis, & Schaie, 1995; Lawton, 1988; Lawton & Brody, 1969).
Managing medications is an important daily task for older adults. In fact, 90% of adults aged 65 years and older take at least 1 prescription medication per week, 40% take at least 5 different medications, and 12% are taking more than 10 types of medications per week (Gurwitz et al., 2003; Zhan et al., 2001). Several available measures of IADL include medication management; however, many are self-report and require only recall (Diehl et al., 1998; Mahurin, DeBettignies, & Pirozzolo, 1991). For example, in the Physical Functioning Inventory, participants are asked how they would obtain medication and whether they have any difficulty taking them (Whetstone et al., 2001), and the timed IADL test requires participants to correctly identify and read the label on a medication bottle in a limited time (Edwards et al., 2005). Assessment of medication skills is limited on most performance measures; however, a measure is needed that more clearly reflects the skills required to manage multiple medications.
The Direct Assessment of Functional Status
The Direct Assessment of Functional Status (DAFS; Loewenstein et al., 1989) has been used to assess the functional status of older adults and their ability to successfully complete IADLs. The 85-item DAFS measures participants' time orientation, communication abilities, transportation knowledge, financial skills, shopping skills, eating skills, and dressing/grooming skills and is administered in outpatient settings. The DAFS has been shown to have high interrater and test–rest reliability among patients identified as possibly having memory disorders and among normal controls. Validity was supported by the significant differences in scores between patients diagnosed with Alzheimer's disease and individuals without cognitive impairment (CI). In addition, DAFS scores were negatively related to scores on the Blessed Dementia Rating Scale among 30 patients with memory impairment. A modified version of the DAFS tested with community elders has been found sensitive to level of cognitive function and dementia (Rankin & Keefover, 1998).
In our SeniorWISE study (McDougall et al., in press) with 265 independent older adults who were screened out for dementia, we found that the DAFS (even excluding the eating and dressing/grooming skills subscales) had a nonnormal distribution on the first administration before intervention or opportunity to practice completing the instrument and also showed a ceiling effect. We used the modified version to take into account the lack of kitchen and bathroom facilities in the evaluation rooms at study sites. The domains measured from the DAFS in this study were time orientation, communication abilities, transportation, financial skills, and shopping skills. A fifth domain, medication skills, was added for the study. Medication skills with three sections (identifying, refilling, and managing medications) was added to more fully capture cognitive tasks that are important for living independently in older age (Table 1 shows the mean, minimum, and maximum scores when administered at baseline in the SeniorWISE study). That is, scores on the DAFS were skewed to the upper end of the distribution (see Figure 1). Furthermore, item analysis of the DAFS showed that many of the items had little to no variation, and participants scored very high despite the fact that two thirds scored in the poor or impaired ranges on the Rivermead test of everyday memory performance (Wilson, Cockburn, & Baddeley, 1991). This pattern of results suggested that the DAFS might not be sensitive to the early deficits in functioning exhibited by older adults experiencing poor memory performance but are still living independently in the community.
(Enlarge Image)
Figure 1.
Frequency histogram of scores on the 85-item Direct Assessment of Functional Status (DAFS) at Time 1 of the SeniorWISE study for the 45 individuals in the present study.
We concluded that a more challenging assessment was needed to test the upper limit of the older adults' skills and detect initial deficits in IADLs that might signal the need for more extensive testing of cognitive function. Also, because correct use of medications is so important for remaining independent, we decided that medication management skills should receive greater emphasis. Consequently, we modified the DAFS and tested the modified version with a subset of SeniorWISE participants approximately 2 years after they completed the study. We revised the instrument with the approval of Dr. David Lowenstein and then examined the psychometric properties of the Direct Assessment of Functional Status-Revised (DAFS-R). This article describes our revision of the DAFS and presents our initial findings on the score distribution, reliability, and validity of the new instrument.