Validation of the Lower Extremity Functional Scale in community-dwelling elderly people (LEFS-Greek); determination of functional status cut-off points using TUG test

PurposeThe aim of this study was to evaluate structural and validity properties of the Greek version of the Lower Extremity Functional Scale (LEFS-Greek) in elderly individuals. Furthermore, to explore the ability of Timed Up & Go (TUG) test as an additional validation criterion.MethodsTwo hundred and two individuals were randomly selected from a large cohort of community-dwelling elderly people with lower extremity musculoskeletal disorders. The structural properties of LEFS-Greek were examined using exploratory and confirmatory factor analysis. The concurrent validity of the instrument was tested against the subscales of the physical functioning and role physical SF-36® Health Survey-Greek version and the TUG test. Known-groups validity was examined to assess questionnaire's ability to discriminate participants into subgroups according to their use of a cane. The cut-off points of the LEFS-Greek were obtained by ROC analysis using the TUG test as external criterion.ResultsFactor analysis demonstrated that the scale has a single-factor structure. LEFS-Greek was strongly correlated with SF36-PF, SF36-RP and TUG test (0.93, 0.62, and −0.72, respectively; P < 0.001). The questionnaire was able to distinguish between the subgroups (LEFS-Greek subgroup scores 19.70 ± 14.43 vs. 51.03 ± 20.39, respectively; P < 0.001). In ROC analysis the area under the curve for LEFS-Greek was 0.978 (95%CI 0.94–1.02, P < 0.001), with cut-off points at 53, and sensitivity and specificity of 92% and 96% respectively.ConclusionLEFS-Greek is a valid assessment tool that can be used to measure functional ability in individuals with lower extremity musculoskeletal disorders. This is the first study in which specific cut-off points were determined.