How do changes in impairment, activity and participation relate to each other: Results of a study of a group of young ambulatory children with cerebral palsy who have received lower extremity botulinum toxin type-A injections

Introduction. The scope of rehabilitation has broadened to incorporate outcomes representing the International Classification of Functioning, Disability and Health (ICF) framework's levels of 'impairment', 'activity' and 'participation'. Moderate associations have been demonstrated between measures in different ICF levels at a single time, but change score relationships are unknown. Methods. A repeated measures, one-group mixed-methods study evaluated associations between changes in 'impairment', 'activity' and 'participation' 2 months (m) and 6 m after lower extremity Bt-A (an intervention that reduces spasticity). Validated measures included: Tardieu spasticity scale and timed walk ('impairment'); Gross Motor Function Measure [GMFM] and Pediatric Evaluation of Disability Inventory [PEDI] ('activity' ); and Pediatric Society of North America questionnaire [POSNA] ( 'participation'). Analysis of variance and linear regression techniques were used. Predictors included outcome measure baseline and change scores, age and Gross Motor Function Classification Level. A qualitative component involved interviews of mothers for perspectives on outcomes. Results . Thirty-five ambulatory children with CP and parents completed baseline, 2 m and 6 m assessments. At 2 m, there were statistically significant 'activity' and 'participation' gains alongside spasticity reduction in gastrocnemius and hamstring muscles. Function was sustained or improved at 6 m despite recurring spasticity. Baseline relationships were fair to strong for 'impairment' vs. GMFM, PEDI and POSNA, and strong between GMFM, PEDI and POSNA scores. Associations between change scores were fair at best. In each GMFM, PEDI and POSNA outcome model, predictors accounted for < 65 % of change score variation. 'Impairment' change accounted for < 50 % of explained variation. Mothers made similar observations about impairment and functional changes. While mothers believed that spasticity reduction facilitated change, they were unsure how much it influenced skill gain and how much resulted from factors such as development and motivation. Conclusion. Quantitative results and mothers' observations emphasized the complex relationships between changes in 'impairment', 'activity' and 'participation'.