THE ASSISTING HAND ASSESSMENT FOR CHILDREN AND YOUTH WITH BRACHIAL PLEXUS BIRTH INJURY: A STUDY OF VALIDITY AND ITEM HIERARCHY OF AHA-PLEX

OBJECTIVE: Functional assessments that focus on activity performance and that produce valid outcome measures for people with brachial plexus birth injury are lacking. The primary aim of this study was to re-evaluate the internal scale validity of the Assisting Hand Assessment specifically for children and adolescents with brachial plexus birth injury. Two further aims were investigating whether the scale could be shortened for this group while maintaining psychometric quality, and exploring and presenting its item difficulty hierarchy. DESIGN: A cross-sectional psychometric study. SUBJECTS: A convenience sample of 105 children and adolescents (aged 18 months to 18 years, mean 6 years, 7 months, standard deviation (SD) 4 years, 4 months) from Sweden, Norway, and the Netherlands with brachial plexus birth injury. METHODS: Participants were assessed with the Assisting Hand Assessment. Data were analysed with Rasch measurement analysis. RESULTS: The 20 Assisting Hand Assessment items together measured a unidimensional construct with high reliability (0.97) and the 4-level rating scale functioned well. Item reduction resulted in 15 items with good item fit, unidimensionality, reliability and acceptable targeting. CONCLUSION: Assisting Hand Assessment for people with brachial plexus birth injury, called AHA-Plex, has 15 items and good internal scale validity. A unique item hierarchy for people with brachial plexus birth injury is presented. LAY ABSTRACT The Assisting Hand Assessment measures how well children and youth with disability on one side of the body use their affected hand in bimanual activities. This test is used in research and by occupational therapists worldwide to plan and evaluate treatment. Previous research has shown that the latest version of Assisting Hand Assessment is well suited for people with unilateral cerebral palsy up to age 18 years, but it needs to be evaluated for people with brachial plexus birth injury. Assisting Hand Assessment was administered to 105 children and youths with brachial plexus birth injury and analysed with Rasch analysis. The results demonstrated excellent validity of the outcomes and that the test worked better with 15 items than the original 20, which reduces the time it takes to score the test. The analysis also revealed a specific difficulty order of the items, which is useful when planning treatment.