Rasch analysis of items from two self-report measures of motor function: Determination of item difficulty and relationships with children's ability levels
The aim of this article was to determine item measurement properties of a set of items selected from the Gillette Functional Assessment Questionnaire (FAQ) and the Pediatric Outcome Data Collection Instrument (PODCI) using Rasch analysis, and to explore relationships between the FAQ/PODCI combined set of items, FAQ walking scale level, Gross Motor Function Classification System (GMFCS) levels, and the Gait Deviation Index on a common measurement scale.
Rasch analysis was performed on data from a retrospective chart review of parent-reported FAQ and PODCI data from 485 individuals (273 males; 212 females; mean age 9 y 10 mo, SD 3 y 10 mo) who underwent first-time three-dimensional gait analysis. Of the 485 individuals, 289 had a diagnosis of cerebral palsy (104 GMFCS level I, 97 GMFCS level II, 69 GMFCS level III, and 19 GMFCS level IV). Rasch-based person abilities and item difficulties based on subgroups defined by the FAQ walking scale level, Gait Deviation Index, and the GMFCS level were compared.
The FAQ/PODCI item set demonstrated necessary Rasch characteristics to support its use as a combined measurement scale. Item groupings at similar difficulty levels were consistent with the mean person abilities of subgroups based on FAQ walking scale level, Gait Deviation Index, and GMFCS level.
Rasch-derived person ability scores from the FAQ/PODCI combined item set are consistent with clinical measures. Rasch analysis provides insights that may improve interpretation of the difficulty of motor functions for children with disabilities.
Figures in this publication
Available from: Philip E Gates
[Show abstract] [Hide abstract]
ABSTRACT: Validated measurement scales are essential to evaluating clinical outcomes and conducting meaningful and reliable research. The purpose of this article is to present the clinician and researcher with a contemporary 8-stage framework for measurement scale development based on a mixed-methods qualitative and quantitative approach. Core concepts related to item response theory are presented. Qualitative methods are described to conceptualize scale constructs; obtain patient, family, and other stakeholder perspectives; and develop item pools. Item response theory statistical methodologies are presented, including approaches for testing the assumptions of unidimensionality, local independence, monotonicity, and indices of model fit. Lastly, challenges faced by scale developers in implementing these methodologies are discussed. While rehabilitation research has recently started to apply mixed-methods qualitative and quantitative methodologies to scale development, these approaches show considerable promise in advancing rehabilitation measurement.
[Show abstract] [Hide abstract]
ABSTRACT: To investigate the relationships between changes in motor capacity (can do, in standardized environment), in motor capability (can do, in daily environment), and in motor performance (does do, in daily environment) among children with cerebral palsy (CP).
Prospective longitudinal study. After baseline measurements (at the age of 18 months, 30 months, 5 years, 7 years, 9 years, 11 years, or 13 years), 2-year follow-up measurements were performed. Change-scores were calculated and Pearson correlations were used for change-score-relationships.
A clinic-based population of children with CP.
Toddlers, school-age children, and adolescents with CP (N=321; 200 boys and 121 girls). Levels of severity according to the GMFCS: Level I 42%, Level II 15%, Level III 17%, Level IV 13%, and Level V 13%.
Not applicable MAIN OUTCOME MEASURES: Change in motor capacity was assessed with the Gross Motor Function Measure-66. Change in motor capability and motor performance were assessed with the Pediatric Evaluation of Disability Inventory, using the Functional-Skills-Scale and Caregiver-Assistance-Scale, respectively.
Within the total group, change-score-correlations were moderate (between 0.52 and 0.67) and significant (p<0.001). For age groups, correlations were significantly higher in toddlers compared with school-age children and with adolescents. For severity levels, correlations were significantly higher in children at level III compared with level I, IV, and V.
Results imply that change in motor capacity does not automatically translate to change in motor capability, nor that change in motor capability automatically translates in change in motor performance. Results also show different relationships for clinically relevant subgroups. These are important insights for clinical practice as it can guide evidence-based interventions with a focus on activities.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.