The comparative ability of eight functional mobility tests for predicting falls in community-dwelling older people.

Background: numerous tests have been suggested as fall risk indicators. However, the validity of these assessments has not been demonstrated in large representative samples of community-dwelling older people.
Objective: the objective of this study was to examine the comparative ability and clinical utility of eight mobility tests for predicting multiple falls in older community-dwelling people.
Methods: design--prospective cohort study; subjects--362 subjects aged 74-98 years; measurements--the sit-to-stand test with one and five repetitions, the pick-up-weight test, the half-turn test, the alternate-step test (AST), the six-metre-walk test (SMWT) and stair ascent and descent tasks. Falls were monitored for 1 year with fall calendars.
Results: in the 12-month follow-up period, 80 subjects (22.1%) suffered two or more falls. Multiple fallers performed significantly worse than non-multiple fallers in the sit-to-stand test with five repetitions (STS-5), the AST, the half-turn test, the SMWT and the stair-descent test. When dichotomised using cut-off points from receiver-operated characteristics (ROC) curve analyses, these tests demonstrated reasonable sensitivity and specificity in identifying multiple fallers. A principal components analysis identified only one factor underlying the mobility tests. Poor performances in two mobility tests, however, increased the risk of multiple falls more than poor performance in one test alone (ORs = 3.66, 95% CI = 1.44, 9.27 and 1.61, 95% CI = 0.62, 4.16 respectively).
Conclusions: the mobility tests appear to be measuring a similar 'mobility' construct. Based on feasibility and predictive validity, the AST, STS-5 and SMWTs were the best tests.