VALIDATION OF AN AUTOMATED UP-TIMER FOR MEASUREMENT OF MOBILITY IN OLDER ADULTS

Objective: To test the reliability, validity and utility of an ''up-ti mer'', an automated device to measure time spent standing and walking. Design: Repeat measurement of mobility one week apart in a convenienc e sample.Setting: Hostel and nursing homes in Melbourne. Participants: 26 hostel and 24 nursing home residents (aged 70-99 years) participat ed. They were mobile, with or without the use of walking aids or perso nal assistance. Outcome measures: ''Up-time'' (measured with the up-ti mer); functional activity (measured with the Barthel Index, Functional Independence Measure, Timed Up & Go, and Human Activity Profile); and disability (measured by the Rapid Disability Rating Scale). Results: The test-retest reliability of the up-timer was high (Pearson's r=0.84 ; P<0.001). Pearson's correlation between the up-timer results and res ults of functional and disability measures ranged from r=0.47 to r=0.5 5. The functional measures correlated more highly among themselves (r= 0.79 to r=0.92). The performance-based Timed Up & Go test had moderate levels of correlation with both the up-timer and the functional measu res. Use of the device was well accepted by both participants and staf f. Conclusions: The up-timer is a practical, objective and reliable me ans of measuring mobility. The useful information it provides is diffe rent from, but overlaps with, that obtained from subjective observatio n or self report. It will complement existing subjective and performan ce-based measures of activity and mobility.