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Carlos Weiss, PI

Year 1:  “Development of a new protocol to measure early-stage disability,” Carlos Weiss, PI, 9/1/09-8/31/10

A major challenge to understanding the causes and progression of disability is that behavior, device use, and the surrounding environment change alongside and in response to physical impairments.  As the WHO’s ICF model illustrates, disability emerges through the interaction between a person and her circumstances (Whiteneck, 2006).  These interactions are not only a possible source of measurement error, but may also influence the trajectory of functional ability itself (Agree, 1999.)    Despite the importance of interactions between a person with physical capabilities and the environment, performance-based measurement of disability have rarely accounted for behavioral or environmental variation (Keysor, 2006).  Using a single set of conditions makes it impossible to understand if and how performance would be affected by change in conditions.

The goal of this pilot project is to develop methods that can be validated for use in large, population-based studies to measure the course of physical disability in older adults in ways that can take environmental variation into account.  Specifically, we proposed to pilot an innovative home-based protocol and determine whether it can reliably measure the effect of task modification on physical performance with standardized equipment and to establish protocol acceptability and safety for participants.

We proposed to obtain measures under standardized settings following established protocols, then under altered conditions.  Modified chair stands were used that extended established procedures (Guralnik et al., 1994).  Reasons for failure to attempt or complete the test were documented.  Drawing on existing instruments (Bellamy et al., 1998; Lamb et al., 2000), we developed simple visual analog scales to study the effect of the condition change on performance in four dimensions: 1) task speed; 2) reported pain; 3) fatigue; and, 4) perceived safety.