Timed "Up & Go" test: reliability in older people dependent in activities of daily living--focus on cognitive state.

BACKGROUND AND PURPOSE It is unknown how cognitive impairment affects the reliability of Timed "Up & Go" Test (TUG) scores. The aim of the present study was to investigate the expected variability of TUG scores in older subjects dependent in activities of daily living (ADL) and with different levels of cognitive state. The hypothesis was that cognitive impairment would increase the variability of TUG scores. SUBJECTS Seventy-eight subjects with multiple impairments, dependent in ADL, and living in residential care facilities were included in this study. The subjects were 84.8+/-5.7 (mean+/-SD) years of age, and their Mini-Mental State Examination score was 18.7+/-5.6. METHODS The TUG assessments were performed on 3 different days. Intrarater and interrater analyses were carried out. RESULTS Cognitive impairment was not related to the size of the variability of TUG scores. There was a significant relationship between the variability and the time taken to perform the TUG. The intraclass correlations were greater than .90 and were similar within and between raters. In repeated measurements at the individual level, an observed value of 10 seconds was expected to vary from 7 to 15 seconds and an observed value of 40 seconds was expected to vary from 26 to 61 seconds for 95% of the observations. DISCUSSION AND CONCLUSION The measurement error of a TUG assessment is substantial for a frail older person dependent in ADL, regardless of the level of cognitive function, when verbal cuing is permitted during testing. The variability increases with the time to perform the TUG. Despite high intraclass correlation coefficients, the ranges of expected variability can be wide and are similar within and between raters. Physical therapists should be aware of this variability before they interpret the TUG score for a particular individual.