Impact of Chronicity on Outcomes Following Post-Hospital Residential Brain Injury Rehabilitation: Application of Multivariate Statistics and Rasch Analysis

This study evaluated the impact of chronicity (onset of injury to admission in-terval) on three domains of functional outcomes for a large group of traumatic brain injured (TBI) survivors. Subjects included 528 TBI adults who were treated in post-hospital residential rehabilitation centers. Subjects were assigned to one of three chronicity groups: 1) Early Interval (EI), 2.00 - 8.00 months n = 245, 2) Mid Interval (MI), 8.01 - 24.00 months n = 129, and (3) Late Interval (LI), 24.01 months and greater n = 154. Functional status was assessed with the MPAI-4. RM MANCOVA was applied to evaluate differences among groups from admission to discharge. Rasch analysis demonstrated satisfactory construct validity and internal consistency (Person reliability = 0.90 - 0.94, Item reliability = 0.99) for the admission and discharge MPAI-4s. Controlling for LOS and age, the RM MANCOVA revealed that each chronicity group showed significant improvement in MPAI-4 abilities, adjustment, and participation indices from admission to discharge (p < 0.001). Improvement observed from admission to discharge was the greatest among the EI group (p < 0.001). This study demonstrated the utility of multivariate statistical approaches for understanding the complexities of TBI treatment outcomes. As measured across three domains of functioning, rehabilitation was effective in reducing disability for participants in each chronicity group. Of the three groups, EI participants presented as the most disabled at admission but also made the greatest gains when assessed at discharge.