Background: The early assessment of prevalent disability and functional decline is of increasing importance for prevention issues and for the evaluation of change in clinical studies. The assessment of common daily tasks and resulting disability is essential for a complete impression of a patient's capabilities. There are plenty of instruments that cover basic and instrumental activities of daily living by assessing the person's dependence at a specific functional task. However, the early stages of everyday life limitations and functional decline are usually not being captured. In this article we have examined psychometric properties of the German adaptation of the abbreviated "late life function and disability instrument", a promising tool that is capable of capturing early aspects of functional decline and disability.
Methods: Older Caucasian men and women (Median=82 years) with a wide range of functional status (Short Physical Performance Battery: Median=6, Min.=0, Max.=12) completed the abbreviated version of the LLFDI once (n=173). A subgroup was assessed twice to examine interrater (n=13) and intrarater (n=10) reliability. Cognitive and functional status was assessed at baseline.
Results: Internal consistency (Cronbach's ) was acceptable for the personal role and social role of the frequency items of the disability component (0.55 to 0.62) and very good for all other parts of the instrument (0.78 to 0.89) without a significant difference when compared for overall cognitive performance or executive function. Test-retest reliability was very good (0.81 to 0.96) and interrater reliability was acceptable to very good (0.62 to 0.96) with only acceptable results for the limitation items of the disability component. The total scores of the two components did not demonstrate significant floor or ceiling effects and the interview lasted on average 17 minutes (range 8 to 35 min).
Interpretation: The German adaptation of the abbreviated version of the "Late Life Function and Disability Instrument" has minimal ceiling and floor effects, acceptable to good internal consistency and interrater reliability, and very good test-retest reliability. Hence, it constitutes an excellent alternative to common self-rating instruments for the assessment of functional capacities in everyday activities.