Psychometric evaluation of the leg activity measure (LegA) for outcome measurement in people with brain injury and spasticity

Purpose: The aim of this study is to evaluate the properties of the Leg Activity measure according to COnsensus-based Standards for the selection of health Measurement INstruments. Method: Participants were assessed at baseline, one day, 6 weeks and 12 weeks, following treatment for leg spasticity with botulinum toxin and physical interventions. Results: In stage 1, 64 participants were recruited to evaluate the initial psychometric properties of Leg Activity measure. In stage 2, 100 additional participants were recruited, to evaluate the scaling properties. Total sample of 164 participants was used. Construct validity was supported for passive function, active function and impact on quality of life. Cronbach's alpha was 0.86, 0.97 and 0.87 respectively for the scales. Item level test-retest agreement ranged from 91-97% (Kappa 0.75-0.95). Following treatment for spasticity (n = 64), the Leg Activity measure passive function and impact on life scales were responsive to change. Principal components analysis confirmed the constructs and a unidimensional Rasch Partial Credit Model was subsequently established for each scale. Transformation to an interval scale was achieved. Using the ordinal-to-interval conversion tables, parametric statistical analysis may be used. Conclusion: The study provides support for the Leg Activity measure being valid, reliable and responsive.

Automated summary

This study aimed to evaluate the properties of the Leg Activity measure based on the Standards for health Measurement Instruments selection. The results showed good psychometric properties and validity of the measurement, with responsiveness demonstrated in participants after treatment for leg spasticity. The analysis confirmed the reliability and validity of the Leg Activity measure in measuring passive function, active function, and impact on quality of life.