We have upgraded the Late-Life Function and Disability CAT. The new version,
Current Pilot Study
Title: Identifying disability in older adults using accelerometery: Can we do better than self-report?
Daniel K. White, PT, ScD
Disability in daily life activities, such as difficulty caring for one-self or going out to public places, are an important and meaningful health outcomes in aging research. To date, there are few self-report measures that demonstrate satisfactory psychometric properties to capture disability, such as the Pepper Assessment Tool for Disability (PAT-D) or the Late-Life Disability Instrument (LLDI), and at present there are no objective measures of disability. There are several notable disadvantages to self-report, including bias due to contextual influences such as cognitive impairment and limited precision, which decreases generalizability across different patient populations and sensitivity to change. One promising complementary approach to measuring disability may be to use accelerometery. Many important daily life activities have unique movement patterns which can be captured by an accelerometer-enabled monitor. For this reason, activity data recorded using triaxial accelerometers may contain features, or unique patterns of activity which are indicators of disability. For instance, the Actigraph is a triaxial accelerometer enabled monitor that quantifies free-living movement in units of activity counts, which is a measure of total energy expenditure. In a pilot study, we recently compared Actigraph data with disability as measured by the LLDI in 70 older adults. We found low variability of sustained bouts of activity counts and low peak 5 and 10 minute activity counts to be correlated with disability as defined as perceived limitation with important daily life activities. Now, we are seeking to employ more sophisticated classification techniques using data sets from larger older adult cohorts to examine disability from accelerometer data.
The overall objective of this proposal is to examine the utility of using accelerometry as a measure of disability in older adults. We will first identify unique features from accelerometry data that demonstrate concurrent validity with self-report measures of disability. Since there is no gold standard measure of disability, we will next examine which measure of disability (self-report or accelerometry) is more sensitive to change over two years. We acknowledge that disability covers a broad spectrum of behaviors many of which may or may not be captured by accelerometery. Therefore, in addition to examining disability as defined by global summary scales, we propose to examine disability behaviors that involve some physical mobility where accelerometery may be of greatest use, such as limitations with recreational activities and visiting family and friends.
Specific Aims and Hypotheses
- To validate features from accelerometry with self-reported measures of disability in older adults. Features derived from accelerometry will be correlated with self-reported measures of disability defined from summary scales as well as from individual items of disability that involve physical mobility.
- To compare sensitivity to change in disability over two years measured with accelerometry to self-reported measures of disability in older adults.
Measures of disability from accelerometry will demonstrate larger effect sizes and standardized response means and a higher proportion of older adults will meet minimum detectable change (MDC) criteria measured by accelerometry compared with self-reported measures of disability.