Intra-individual variability in recovery from paediatric acquired brain injury: Relationship to outcomes at 1 year

OBJECTIVE: To determine the relationship between the amount of intra-individual variability in measures of abilities and participation throughout the first 8 months of recovery from ABI and outcome scores at 1 year. Greater amounts of intra-individual variability throughout recovery are hypothesized to predict better outcome scores at 1 year. RESEARCH DESIGN: This is a secondary data analysis of a longitudinal cohort study. METHODS: Eighty-seven children and youths were assessed with self and proxy report measures of child functioning, family functioning and environmental factors at regular intervals after ABI. Mixed-effects modelling was used to determine individual linear recovery trajectories. Intra-individual variability was defined as the intra-individual standard deviation of the residuals around the recovery line. RESULTS: Less intra-individual variability in recovery predicts better outcomes of physical health (Child Health Questionnaire), behavioural functioning (Strengths and Difficulties Questionnaire), family coping (Impact on Family Scale) and impact of environmental barriers (Craig Hospital Inventory of Environmental Factors). As amount of intra-individual variability increases, outcomes become poorer. CONCLUSIONS: Findings support the existence of intra-individual variability in instrument scores over time in this sample and the impact of this variability on several outcomes at 1 year. Potential clinical and research implications are discussed.