A Revised Activities of Daily Living/Instrumental Activities of Daily Living Instrument Increases Interpretive Power: Theoretical Application for Functional Tasks Exercise

Abstract

Background: As the number of adults in older age groups expands, difficulty performing usual activities of daily life is a rising health concern. A common exercise regimen employed to attenuate functional decline and disability has been resistance strength training. However, recent evidence suggests that functional tasks exercise may be more effective in preventing disability. Objective: Activities of Daily Living (ADL) measures are one of the most widely used tools in gerontology, and yet the full sensitivity of these instruments is often not realized. The purpose of this study is to enhance the interpretive power of ADL by formally confirming a hierarchy of decline, assessing discriminatory power, and examining option characteristic curves. Theoretically, a revised ADL instrument can improve the efficacy of functional tasks training programs. Methods: This was a cross-sectional study that employed Item Response Theory (IRT) to interpret ADL outcomes. Participants consisted of community-dwelling older adults (n = 548, aged 79) living in Scotland. Results: A Mokken scale with ρ = 0.77 was obtained, indicating good reliability, and satisfying the IRT assumption that a single unidimensional scale is present. The set H coefficient of 0.48 indicated that the scale may be ordered by decreasing difficulty, with the ‘Cut your own toe-nails?’ item being the most difficult and ‘Tie a good knot in a piece of string?’ being the least difficult. Discriminatory and option characteristic parameters revealed ‘Get on a bus?’ to be the task most closely related to the latent construct and that item options can be used to ascertain critical thresholds for prevention type strategies. Conclusions: Examining parameters relating to difficulty, discriminatory power, and option characteristics facilitated the identification of ADL/Instrumental ADL items that may serve to enhance functional task training in community-dwelling older adults. These analyses demonstrated that functional tasks have differing levels of discriminatory power, and that a task’s discriminatory power is likely to change with varying levels of disability. This observation reinforces the notion that exercises based on functional tasks may differ significantly in their therapeutic effect. Lastly, this study was able to highlight statistically meaningful cut-points relating to when older adults should begin ‘prehabilitation’ interventions.

Preliminary testing using Mokken scaling of an Italian translation of the Edinburgh Feeding Evaluation in Dementia (EdFED-I) scale

“…However, in the present study ten items of the EdFED-I were entered into Mokken scaling to see if the feeding behaviors were related to the other nursing interventions and indicator items and to see if these were predictors for feeding difficulty. The rationale was based on recent analysis of the Townsend Activities of Daily Living scale (Fieo et al, 2010) where a case was made for such predictive power of certain items. The resulting rationale is that it may be possible to inaugurate interventions for feeding difficulty earlier in dementia and the imperative for this comes from a line of successful work into feeding difficulty in dementia (Lin et al, 2010).…”

“…However, recent work on activity of daily living (ADL) scales demonstrates that, using hierarchical scaling methods, it is worth including a wider range of items to test the predictive ability of a scale (Fieo, Watson, Deary, & Starr, 2010). In other words, it is worth investigating if are there behaviors or items that can be detected early in a disease process that may indicate subsequent difficulty.…”

Calibrating ADL-IADL scales to improve measurement accuracy and to extend the disability construct into the preclinical range: a systematic review

“…Despite the comprehensive coverage of McHorney and Cohen [69], this manuscript made use of the 2PL IRT model which does not provide the added advantage of invariant item ordering; Ligtvoet et al [22] point out that Sijtsma and Hemker [44] proved that the graded response model used in McHorney and Cohen does not imply invariant item ordering. Invariant item ordering is clinically useful because improved understanding of the sequence of functional change or decline and its natural trajectory in aging would open up opportunities for thinking about early intervention and/or ways to change this trajectory [20,78]. Ligtvoet et al [22] reports that IIO is a strong requirement in measurement practice, and that researchers sometimes assume that fitting an IRT model implies that items have the same ordering by difficulty or popularity for all individuals, but this assumption requires modification.…”

Item response theory analysis of cognitive tests in people with dementia: a systematic review

“…IRT has been used to analyse clinical measures in several different fields: schizophrenia [11], depression [12], attachment [13], social inhibition [14] and quality of life [15]. IRT has also been used to examine ADL and Instrumental Activities of Daily Living (IADL) scales [16,17]. IRT methods have been successful in improving functional scales by establishing interval level measurement [18]; hierarchies of item difficulty [16,19,20]; discrimination of items [16,21]; as well as identifying ways of increasing measurement precision [18].…”

“…IRT has also been used to examine ADL and Instrumental Activities of Daily Living (IADL) scales [16,17]. IRT methods have been successful in improving functional scales by establishing interval level measurement [18]; hierarchies of item difficulty [16,19,20]; discrimination of items [16,21]; as well as identifying ways of increasing measurement precision [18]. IRT analyses of measures of cognitive functioning in the general population have been described [22,23], including several papers with samples including some participants with dementia [24-28].…”