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Comparative Study
. 2011 Apr;51(2):179-89.
doi: 10.1093/geront/gnq087. Epub 2010 Oct 25.

Regression-based estimates of observed functional status in centenarians

Meghan B Mitchell  1 , L Stephen Miller, John L Woodard, Adam Davey, Peter Martin, Molly Burgess, Leonard W Poon; Georgia Centenarian Study
Collaborators, Affiliations
Comparative Study

Regression-based estimates of observed functional status in centenarians

Meghan B Mitchell et al. Gerontologist. 2011 Apr.

Abstract

Purpose of the study: There is lack of consensus on the best method of functional assessment, and there is a paucity of studies on daily functioning in centenarians. We sought to compare associations between performance-based, self-report, and proxy report of functional status in centenarians. We expected the strongest relationships between proxy reports and observed performance of basic activities of daily living (BADLs) and instrumental activities of daily living (IADLs). We hypothesized that the discrepancy between self-report and observed daily functioning would be modified by cognitive status. We additionally sought to provide clinicians with estimates of centenarians' observed daily functioning based on their mental status in combination with subjective measures of activities of daily living (ADLs).

Design and methods: Two hundred and forty-four centenarians from the Georgia Centenarian Study were included in this cross-sectional population-based study. Measures included the Direct Assessment of Functional Status, self-report and proxy report of functional status, and the Mini-Mental State Examination (MMSE).

Results: Associations between observed and proxy reports were stronger than between observed and self-report across BADL and IADL measures. A significant MMSE by type of report interaction was found, indicating that lower MMSE performance is associated with a greater discrepancy between subjective and objective ADL measures.

Implications: Results demonstrate associations between 3 methods of assessing functional status and suggest proxy reports are generally more accurate than self-report measures. Cognitive status accounted for some of the discrepancy between observed and self-reports, and we provide clinicians with tables to estimate centenarians' performance on observed functional measures based on MMSE and subjective report of functional status.

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Figures

Figure 1.
Figure 1.
Domains and skill requirements for the modified Direct Assessment of Functional Status and corresponding self and proxy questions. Note: BADL = basic activities of daily living; IADL = instrumental activities of daily living. Self-report and proxy questions were answered with a score of 2 (without any help), 1 (with some help), or 0 (completely unable to do so alone).
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