Further development of the High-level Mobility Assessment Tool (HiMAT).

The high-level mobility assessment tool (HiMAT) was developed to measure high-level mobility limitations following traumatic brain injury (TBI). Rasch analysis was used in the development to ensure cognitive deficits would have a minimal impact on performance. The main aim of this study was to investigate the dimensionality of the HiMAT using recently developed advanced testing procedures. Results from the original sample of 103 adults with TBI used to develop the HiMAT were re-analysed using the RUMM2020 program. Revised minimal detectable change (MDC(95)) scores were also calculated. MAIN OUTCOMES AND RESUlts: Rasch analysis of all 13 HiMAT items suggested that the scale was multidimensional, showing a clear separation between the stair and non-stair items. The nine non-stair items of the HiMAT showed good overall fit, excellent internal consistency, with no disordered thresholds or misfitting items, however removal of one item was required to ensure a unidimensional scale. The final 8-item solution showed good model fit (p = 0.93), excellent internal consistency (PSI = 0.96), no disordered thresholds, no misfitting items and no differential item functioning for age or sex. The revised HiMAT total score is 32 points and the MDC(95) was calculated to be +/-2 points. The results of this study demonstrate that the revised HiMAT is unidimensional and valid to use in rehabilitation and community settings where there is no access to stairs.