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Background: Interest in measuring functional status among nondisabled older adults has increased in recent years. This is, in part, due to the notion that adults identified as 'high risk' for functional decline portray a state that is potentially easier to reverse than overt disability. Assessing relatively healthy older adults with traditional self-report measures (activities of daily living) has proven difficult because these instruments were initially developed for institutionalised older adults. Perhaps less evident, are problems associated with change scores and the potential for 'construct under-representation', which reflects the exclusion of important features of the construct (e.g., disability). Furthermore, establishing a formal hierarchy of functional status tells more than the typical simple summation of functional loss, and may have predictive value to the clinician monitoring older adults: if the sequence task difficulty is accelerated or out of order it may indicate the need for interventions., Methods: This review identified studies that employed item response theory (IRT) to examine or revise functional status scales. IRT can be used to transform the ordinal nature of functional status scales to interval level data, which serves to increase diagnostic precision and sensitivity to clinical change. Furthermore, IRT can be used to rank items unequivocally along a hierarchy based on difficulty. It should be noted that this review is not concerned with contrasting IRT with more traditional classical test theory methodology., Results: A systematic search of four databases (PubMed, Embase, CINAHL, and PsychInfo) resulted in the review of 2,192 manuscripts. Of these manuscripts, twelve met our inclusion/exclusion requirements and thus were targeted for further inspection., Conclusions: Manuscripts presented in this review appear to summarise gerontology's best efforts to improve construct validity and content validity (i.e., ceiling effects) for scales measuring the early stages of activity restriction in community-dwelling older adults. Several scales in this review were exceptional at reducing ceiling effects, reducing gaps in coverage along the construct, as well as establishing a formal hierarchy of functional decline. These instrument modifications make it plausible to detect minor changes in difficulty for IADL items positioned at the edge of the disability continuum, which can be used to signal the onset of progressive type disability in older adults.

Background/Aims: Dementia exhibits an insidious onset consisting of cognitive, behavioral, and functional impairment. We explored a functional continuum that extends assessment beyond the clinical instrumental activities of daily living (IADL) range and into advanced activities of daily living. Methods: We examined the predictive power (Cox regression; n = 2,471) of a unidimensional IADL-extended (IADL-x) scale for incident mild cognitive impairment (MCI). We also examined “time to MCI” as an outcome measure. Results: Each additional task endorsed on the IADL-x hierarchy (e.g., endorsing participation in 6 vs. 5 activities) resulted in a 10% reduction in MCI risk (HR 0.90, 95% CI 0.85–0.94, p < 0.001). For the fully adjusted model the risk reduction dropped to 6%. The odds of incident MCI within 2 years (for those below the median IADL-x total score) was 2.5 times higher (OR 2.60, 95% CI 1.52–4.4, p < 0.001) and 2 times higher for incident MCI within the next 5 years (OR 1.93, 95% CI 1.76–3.2, p < 0.01). Conclusion: The IADL-x metric appears to be a valid approach for determining the risk of MCI based on one’s position along a formal hierarchy of function. [ABSTRACT FROM AUTHOR]

Aims. To demonstrate the principles and application of Mokken scaling. Background. The history and development of Mokken scaling is described, some examples of applications are given, and some recent development of the method are summarised. Design. Secondary analysis of data obtained by cross-sectional survey methods, including self-report and observation. Methods. Data from the Edinburgh Feeding Evaluation in Dementia scale and the Townsend Functional Ability Scale were analysed using the Mokken scaling procedure within the 'R' statistical package. Specifically, invariant item ordering (the extent to which the order of the items in terms of difficulty was the same for all respondents whatever their total scale score) was studied. Results. The Edinburgh Feeding Evaluation in Dementia scale and the Townsend Functional Ability Scale showed no violations of invariant item ordering, although only the Townsend Functional Ability Scale showed a medium accuracy. Conclusion. Mokken scaling is an established method for item response theory analysis with wide application in the social sciences. It provides psychometricians with an additional tool in the development of questionnaires and in the study of individuals and their responses to latent traits. Specifically, with regard to the analyses conducted in this study, the Edinburgh Feeding Evaluation in Dementia scale requires further development and study across different levels of severity of dementia and feeding difficulty. Relevance to clinical practice. Good scales are required for assessment in clinical practice and the present paper shows how a relatively recently developed method for analysing Mokken scales can contribute to this. The two scales used as examples for analysis are highly clinically relevant. [ABSTRACT FROM AUTHOR]

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. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]