Evaluating and refining the wheelchair mobility activity log (WC-MAL): a comprehensive study of validity and reliability

STUDY DESIGN: Validity and Reliability Analysis. OBJECTIVE: Evaluate the structural validity, reliability and criterion validity of the Wheelchair Mobility Activity Log (WC-MAL) using Rasch analysis. METHODS: Sixty individuals with SCI and using a manual wheelchair participated in the study. The WC-MAL was employed remotely. Rasch analysis evaluated the structural validity of the instrument. The intra-rater reliability of the WC-MAL score was analysed using the random model Intraclass Correlation Coefficient (ICC) and the Standard Error of Measurement was calculated to estimate the precision of individual scores. For concurrent criterion validity, the data from the tachometer were used as the "gold standard" to assess wheelchair mobility, with the WC-MAL serving as the comparator. Pearson's correlation coefficient was used to evaluate the relationship between the tachometer data and WC-MAL Frequency Scale scores. RESULTS: The Rasch analysis led to the exclusion of three items (1, 3, and 10) from the original instrument, improving model fit and refining WC-MAL 2.0. WC-MAL 2.0 demonstrated good discriminant ability with a Person Separation Reliability of 0.91-0.93 and explained variance between 59.3 and 61%. The WC-MAL 2.0 showed no local dependency, maintained unidimensionality across all scales, and exhibited no uniform Differential Item Functioning. The WC-MAL 2.0 demonstrated excellent inter-rater reliability (ICC0.84-0.91), strong internal consistency (Cronbach's alpha 0.84-0.91), and strong correlations between the Frequency Scale and tachometer data (r = 0.78, p < 0.001), supporting its criterion validity. CONCLUSION: The WC-MAL 2.0 is a suitable instrument with adequate validity and reliability for assessing wheelchair performance in individuals with SCI.