Self-Reporting of Capable Versus Typical Functional Activity Performance in Community-Dwelling Older Adults

Objectives: In order to assess the effect of contextual support on self-reported responses of limitations in physical activities in community dwelling older people, this article explores differences in responses when asked about activities conducted (1) without assistive devices or person help, and (2) in the typical manner, including with the support of assistive devices and person help. Methods: A self-report questionnaire of 54 activity items was administered by a trained interviewer to 50 volunteer participants in their homes. Oneparameter item response theory (Rasch) analysis was used to transform ordinal level Likert scale responses into interval level item difficulty estimates (calibrations). These estimates were then compared under the two different conditions: typical versus capable. Results: Self-reported activity limitations on many items, particularly transfer and mobility activities, were influenced by whether assistive devices and person help were considered part of the item definition. Discussion: Specification of whether device or person support is part of the activity definition appears critical in order to achieve accurate measurement of self-report limitations in many physical activities.