Measurement properties of the high-level mobility assessment tool for mild traumatic brain injury

Background. The High-Level Mobility Assessment Tool (HiMAT) was developed to quantify balance and mobility problems after traumatic brain injury (TBI). Measurement properties of the HiMAT have not been tested in the mild TBI (MTBI) population. Objective. The aim of this study was to examine the reliability, validity, and responsiveness of the HiMAT in a sample of the MTBI population. Design. A cohort, pretest-posttest, comparison study was conducted. Methods. Ninety-two patients (69% men, 31% women) with a mean age of 37.1 years (SD 13.8) and a mean Glasgow Coma Scale score of 14.7 (SD 0.7) were recruited from Oslo University Hospital. All patients were tested with the HiMAT (range of scores 0 [worst] to 54 [best]) at 3 months postinjury. Fifty-one patients were retested at 6 months. A subgroup of 25 patients was selected for the reliability testing. Balance function reported on the Rivermead Post Concussion Symptoms Questionnaire was chosen as a criterion and anchor. Criterion-related validity was studied with correlation analysis. Intraclass correlation coefficients (ICCs) were used for assessing interrater and intrarater reliability. Minimal detectable change (MDC) for the HiMAT was estimated. Responsiveness was assessed with receiver operating characteristic curve analyses. Results. The mean HiMAT sum score was 46.2 (95% confidence interval 44.4 to 48.1). The HiMAT had a ceiling effect of 22.8%. The correlation between HiMAT scores and self-reported balance problems was large (r .63, P .001). Interrater and intrarater reliability of the HiMAT sum score was high (interrater ICC .99, intrarater ICC .95). The MDC was 3 to 4 points. Responsiveness was good, and the HiMAT discriminated well between patients with self-perceived improved balance function versus unchanged balance function (area under the curve 0.86). Limitations. The small sample size, a ceiling effect, and lack of a gold standard were limitations of the study. Conclusions. The HiMAT demonstrated satisfactory measurement properties for patients with MTBI. The HiMAT can be used as an outcome measure of balance and mobility problems in patients with MTB