Fried's definition of frailty is widely used but its measurement is problematic. Timed up-and-go (TUG) is a simple measure of mobility that may be a useful proxy for frailty. Here, we describe the distribution of frailty and TUG in the older population of Ireland and discuss the extent to which TUG identifies the frail and prefrail populations.
A total of 1,814 participants of The Irish Longitudinal Study on Ageing aged 65 and older completed a comprehensive health assessment. Frailty was defined by having three or more of low gait speed, low grip strength, unintentional weight loss, self-reported exhaustion, and low physical activity. ROC curves were used to identify how well TUG discriminates the frail and prefrail populations and whether TUG improves on gait speed as a single objective measure of frailty.
Among the Irish population aged 65 and older, 7.7% were frail and 44.0% were prefrail. TUG identifies frail members of the population well (AUC = 0.87) but is less able to discriminate the nonfrail from the prefrail or frail populations (AUC = 0.73). TUG captures the components of frailty that become more common with age but does not discriminate the components that do not, for example, unintended weight loss or exhaustion. There is no advantage in using TUG instead of gait speed with respect to identifying frailty.
TUG is a sensitive and specific measure of frailty that offers advantages in its measurement where the full application or interpretation of Fried's criteria is impracticable; however, TUG cannot be used to reliably identify prefrail individuals.