Reliability and validity of the L test in people with multiple sclerosis

Objectives

Functional mobility is an essential factor affecting the activities of daily living in people with multiple sclerosis (PwMS). The L test is a comprehensive assessment tool for functional mobility that incorporates sit-to-stand, transfers and bidirectional turning. The purpose of this study was to determine the psychometric properties of the L test in PwMS.

Design

Cross-sectional study.

Participants

Thirty-four PwMS [Expanded Disability Status Scale (EDSS) score 0 to 5] and 34 healthy controls were included in this study.

Main outcome measures

The L test was administered along with the timed up and go (TUG) test, 10-m walk test (10-MWT), 6-minute walk test (6-MWT), timed 360 degree turn test, and EDSS by the same rater. Fall history was recorded to categorize PwMS with and without a history of falls. The L test was repeated after 1 week to determine test–retest reliability.

Results

The L test showed excellent test–retest reliability (intraclass correlation coefficient 0.995). The minimum detectable change for the L test time was 1.4 seconds. The L test demonstrated significant positive correlations with the TUG test, timed 360 degree turn test and EDSS score, and significant negative correlations with the 10-MWT and 6-MWT (P < 0.001). Significant differences in the L test times were found between PwMS and healthy controls, and between PwMS with a history of falls and those without a history of falls (P < 0.05). The cut-off time of 14.7 seconds on the L test was found to best discriminate between PwMS and healthy people, while 16.4 seconds was found to best discriminate between PwMS with a history of falls and those without a history of falls.

Conclusion

The L test is a reliable and valid tool for the assessment of functional mobility in PwMS.

Clinical Trial Registration number

NCT05641714.

Contribution of the Paper

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  The L test has excellent test–retest reliability and validity in PwMS.
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  The L test can provide insight into functional mobility, with high scores (long completion times) warranting further specific assessment of underlying components (turning, walking, etc.) that may contribute to the longer completion times.
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  The L test demonstrates a more comprehensive mobility assessment using an L-shaped pathway.