Internal validity of the revised HiMAT for people with neurological conditions.

The High-level Mobility Assessment Tool (HiMAT) was developed to measure high-level mobility limitations following traumatic brain injury. The aim of this study was to investigate if the revised HiMAT is valid for use with adults with neurological conditions other than traumatic brain injury. Cross-sectional study. Ninety-five participants with neurological conditions. HiMAT score sheets were retrieved from the central medical files of people who had attended a major rehabilitation facility for a neurological condition from January 2006 to October 2007. Additional HiMAT score sheets were submitted by therapists who participated in the HiMAT User's Group. Rasch analysis (RUMM2030 software) was used to determine the overall fit of the model, individual item fit and differential item functioning. Rasch analysis supported the internal validity of the revised eight-item HiMAT for individuals with neurological conditions. It showed good overall fit (P = 0.74), no misfitting items and excellent internal consistency (Person Separation Index = 0.91). The HiMAT is unidimensional with no evidence of response dependency and no differential item functioning for age or sex. Further development of the revised HiMAT is required to investigate other aspects of validity, reliability and responsiveness in different neurological populations. However, the results support the internal validity of the revised HiMAT when used for people with neurological conditions who are able to walk without gait aids.