Background: The measurement of physical disability as an indication of the impact of disease is commonly seen in research. However, these measures often do not clearly differentiate between functional limitations and daily performance of an activity.
Methods: We measured the differences between self-reported disability and observed functional limitations in six activities of daily living tasks among community-dwelling elders. The value of functional limitations vs disability measures in determining risk factors for disablement was ascertained.
Results: Systematic differences were found among the 1453 participants. At least 89% of the time when a difference was identified, the subjects ranked disability greater than the functional limitations observed. For those who were cognitively impaired, discrepancies occurred up to 11% of the time. In determining risk factors for disablement, we found that neurological impairments were associated with both functional limitations and disability, while sociocultural factors were associated with disability only.
Conclusions: Our findings suggest that physical functional limitations and disability in the elderly are two distinct concepts and that the measure of choice should be determined by research objectives and the type of population being studied.