A Comprehensive Evaluation of Mobility: Validation of the Functional Ambulation and Stair Test in Older Adults

Background/Objectives: Falls have devastating consequences for older adults. The Functional Ambulation and Stair Test (FAST) was developed to characterize older adult mobility and eventual fall risk. This project aimed to determine the criterion validity of the FAST assessment by comparing the relationship between FAST outcomes and existing gold-standard clinical assessments of mobility and fall risk. A secondary aim was assessing the FAST's capacity to elicit dual-task effects in older adults. Methods: The FAST is a multi-faceted mobility assessment combining stair navigation, turning and level-ground walking; total time and time spent in each phase are the calculated outcomes. Data from 199 older adults completing the FAST, Berg Balance Scale (BBS), Timed Up and Go (TUG), and Ten Meter Walk Test (10MWT) at comfortable and fast speed were evaluated. Relationships between the FAST and clinical outcomes were evaluated with Spearman's correlations. The FAST and TUG were assessed under single- and dual-task conditions; linear mixed models evaluated the dual-task effects for overall FAST time and each phase. Results: Spearman's correlations between the FAST and the BBS, TUG, 10MWT comfortable and 10MWT fast were -0.65, 0.88, -0.79, and -0.83, respectively. Participants experienced an 8.6% and 13.2% dual-task cost in the FAST and TUG, respectively. The greatest dual-task cost during the FAST was in the gait initiation, walking, and wide turn phases. Conclusions: Agreement between the FAST and gold-standard clinical mobility assessments confirms the criterion validity of the FAST. Delineation of mobility phases via the FAST offers insight into specific mobility deficits. Future work is ongoing to evaluate the FAST as a fall risk assessment in older adults.