Rasch Properties of the Cognitive and Linguistic Scale and Optimization for Outcome Trajectory Modeling in Pediatric Acquired Brain Injury.

Abstract Objectives: To (1) determine if items on the Cognitive and Linguistic Scale (CALS) follow a Rasch distribution and (2) explore the relationship between Rasch-derived Cognitive Ability Estimates (CAE) and outcome trajectory parameters using a nonlinear mixed effects modeling approach. Design: Retrospective study. Setting: Pediatric inpatient rehabilitation hospital. Participants: 252 children between the ages of 2 and 21 years (median 11.8; interquartile range [IQR] 6.4-15.9) consecutively admitted to an inpatient rehabilitation brain injury unit (2008-2014) for a first inpatient admission following acquired brain injury. Interventions: Not applicable. Main Outcome Measures: Rasch-derived CAE from the CALS and associated outcome trajectory parameters. Results: The CALS demonstrates adequate interval-scale properties with removal of scores from the arousal and responsivity items. Rasch-derived CAE were associated with age ( β =.025, p =.000) such that older age was associated with a faster rate of recovery and more complete ultimate recovery. Slower recovery initiation was associated with a less complete overall cognitive recovery (Spearman ρ = -0.31; p =.000). Conclusions: The CAE derived from the CALS and associated outcome parameters (e.g., rate of recovery) may serve as an ideal outcome measure for clinical trials evaluating interventions for acquired brain injury in a pediatric rehabilitation setting.