Modelling early recovery patterns after paediatric traumatic brain injury

Objective: To describe the range of early recovery patterns seen in children admitted for inpatient rehabilitation after traumatic brain injury and to build simple predictive models of expected recovery. Patients: 103 consecutive paediatric admissions to a neurological rehabilitation facility after closed head injury. Methods: Children's recoveries were defined by repeated scores on the WeeFIM (a validated paediatric measure of functional independence) assembled into recovery trajectories. Non-linear mixed effects modelling was used to define 'typical' recoveries and to identify useful simple predictor variables. Results: WeeFIM recovery curves showed a characteristic sigmoidal form with an initial slow phase followed by a mid-phase of fastest improvement and a late plateau. Final WeeFIM scores ranged from 18 to 125 (median 105, IQR 87-117). The time taken to reach 50% final WeeFIM score ranged from 5 to 145 days (median 27, IQR 17-46). Both final WeeFIM and time to reach 50% final WeeFIM correlated with time to follow commands (TFC), defined as the post-injury day on which a child was first observed to follow two simple commands in a 24 h period. Conclusions: Simple models predicting outcome trajectory can be built incorporating early rate-of-recovery indices (such as TFC) as proxies of injury severity. Such models allow informed discussion with families of likely rates of progress and the CI on these estimates. Models of this nature also potentially allow identification of children making better- or worse-than-expected recoveries.