Reliability and validity of the novel-lower extremity dexterity assessment in people with multiple sclerosis

Lower extremity dysfunctions are earlier and more prominent than upper extremity dysfunctions in multiple sclerosis (MS). The loss of dexterity is well-documented and there are several outcome measures that evaluate dexterity in the upper extremity of people with MS (PwMS). However, the assessment tool for the lower extremity dexterity has not been available in MS. The novel lower-extremity dexterity assessment (NLEDA) evaluates lower extremity dexterity. Thus, the aims of this study investigate: (1) the test-retest reliability, standard error of measurement (SEM), and minimum detectable change (MDC) in the NLEDA times; (2) the concurrent and known-groups validity of the NLEDA; and (3) the cut-off times that best discriminate fallers from non-fallers with MS.

This cross-sectional study included 49 PwMS with an Expanded Disability Status Scale (EDSS) score <7.0 and 49 healthy people. The NLEDA was administered along with the nine-hole peg test, 10-meter walk test, timed up and go test, Berg Balance Scale, activities-specific balance confidence scale, and EDSS. The NLEDA was repeated 7-10 days apart for test-retest reliability.

The NLEDA had excellent test-retest reliability with an intraclass correlation coefficients of 0.966 and 0.971 for the dominant and non-dominant feet, respectively. The SEM and MDC were 1.35 s and 3.74 s, respectively for the dominant foot, while they were 1.17 s and 3.24 s, respectively for the non-dominant foot. The NLEDA correlated with other measures (p<0.001). For both feet, significant differences in the NLEDA times were found between PwMS and healthy people and between fallers and non-fallers with MS (p<0.001 and p<0.001, respectively). The cut-off times of 17.62 s and 16.40 s on the dominant and non-dominant feet, respectively best discriminated fallers from non-fallers with MS.

The NLEDA is a reliable, valid, and clinically available tool for PwMS with EDSS score <7.0. It shows potential and provides preliminary evidence which should be confirmed in future studies with larger sample sizes.