Special Interest Report
Population: Pediatric
Doreen J Bartlett, PT PhD, Professor, University of Western Ontario djbartle@uwo.ca
Lisa Chiarello, PT PhD PCS FAPTA, Professor, Drexel University, Department of Physical Therapy and Rehabiliation Sciences lc38@drexel.edu
Keywords: Prediction, developmental change, cerebral palsy
Purpose: One goal of pediatric physical therapy is to optimize the outcomes of a condition through effective interventions. Identification of determinants of change over time (i.e. prognostic factors), if modifiable, provide foundational knowledge to inform the focus of therapy.1 We share our experiences about conceptualizing and testing determinants of change in basic gross motor abilities of young children with cerebral palsy (CP).
Description: Our team has described the development2 and plans for testing3 of a conceptual model of determinants of gross motor function, and participation in self-care, recreation and leisure, and play of young children with CP. The model is compatible with current conceptualizations of functioning, disability and health, systems theory, theories of human ecology, and an approach incorporating family-centred care, as well as being based on research literature, clinical expertise, and input from parent collaborators.2 The model emphasizes the multisystem complexity of a child with CP and the dynamic interaction between the child and his or her environment. Data were collected on selected primary and secondary impairments, associated health conditions, adaptability, and gross motor function at the beginning of the one-year study. Data on family ecology and community programs and rehabilitation services were collected 7 months later, and gross motor function was measured again at the end of the year. When tested, although the data were a good fit with the model, it explained 9-13% of the variance in change of motor function of 429 young children with CP over a period of 1 year, in contrast to 58-75% of the variance in motor function when the outcome was conceptualized as simply motor function at the end of the year.4 This surprising finding was not explained by lack of variability in the change scores, averaging 5 points with an interquartile range of 8 points. We speculate that this result is attributable to the complexity, uniqueness, and non-linearity of developmental phenomena.5
Summary of Use: Predicting developmental change is difficult. Across a range of developmental domains (i.e. of both determinants and outcomes in any prognostic model), child development does not occur at a steady pace, but instead progresses in spurts and plateaus over time,6,7 with typically a lack of correspondence in rate of development among trajectories of various domains.8 Also, a unit of change in a determinant is not necessarily associated with a unit change in outcome; a small incremental change in a determinant, such as muscle strength, can lead to significant motor function advances.5 It is also possible that developmental change is not a generalizable phenomenon,5 especially for children with CP who demonstrate wide inter-individual variation.
Importance to Members: As have others,9 we conclude that it is more realistic to pursue investigation of prediction of future function rather than change in function. The complexities of children with CP also suggest that expertise,10 in addition to evidence, is required to optimize intervention outcomes.
Citation:
Bartlett, Doreen J, PT PhD; Chiarello, Lisa A, PT PhD PCS FAPTA. Difficulties in Predicting Developmental Change.. Poster Presentation. IV STEP Conference, American Physical Therapy Association, Columbus, OH, July 17, 2016. Online. https://u.osu.edu/ivstep/poster/abstracts/090_bartlett-chiarello/