JMIR Publications

ABSTRACT

Background:

The Timed Up and Go Test (TUG) is recommended as an evidence-based tool for measuring physical ca-pacity. Instrumented TUG (iTUG) approaches expand classical supervised clinical applications offering the potential of self-assessment for older adults.

Objective:

The objectives of this study were to evaluate the concurrent validity and test-retest reliability of a smartphone-based TUG self-assessment (“up&go app”).

Methods:

Fifty-two community-dwelling older adults (>67 years) were recruited. A validated and medically certified system attached with a belt at the lower back was used as a reference system to validate the “up&go app” algorithm. The participants repeated the TUG five times wearing (1) a smartphone with the “up&go app” in the front trouser pocket and (2) an intertial sensor to test the concurrent validity. A subsample of 37 participants repeated the “up&go app” measurement two weeks later to examine the test-retest reliability.

Results:

The correlation between the “up&go app” and the reference measurement was r=0.99 for the total test duration and r=0.97 for the five single repetitions. Agreement between the five repetitions was ICC=0.90 [0.84-0.94]. Leaving out the first repetition, the agreement was ICC=0.95 [0.92-0.97]. Test-retest agreement had an ICC = 0.79 [0.53-0.90].

Conclusions:

The duration of five repetitions of the TUG test, measured with the pocket-worn “up&go app”, was very consistent with the results of a lower-back sensor system, indicating excellent concurrent validity. Partic-ipants walked slower in the first round compared to the other four repetitions within a test run. Test-retest reliability was also excellent. The “up&go app” provides a useful smartphone-based approach to measure five repetitions of the TUG. The app could be used by older adults as a self-screening and moni-toring tool of physical capacity at home and thereby help to early identify functional limitations and take interventions when necessary.