Gross Motor Family Report: Refinement and evaluation of psychometric properties

Abstract

AbstractAimTo refine the Gross Motor Family Report (GM‐FR) using parents' input and to evaluate its psychometric properties.MethodIn this measurement study, 12 parents of children and adolescents with cerebral palsy (CP), aged 2 to 18 years, classified in all levels of the Gross Motor Function Classification System (GMFCS), were interviewed about their experience completing the GM‐FR (content validity). Parents' feedback was used to refine the measure which was then completed by 146 families to evaluate internal consistency, and discriminative and concurrent validity. Forty‐six parents completed the GM‐FR again, 7 to 30 days later, to evaluate test–retest reliability.ResultsGM‐FR scoring, pictures, descriptions, and the total number of items were revised based on parents' feedback. The GM‐FR version 2.0 demonstrated high internal consistency (Cronbach's α = 0.99), no floor/ceiling effects, and excellent test–retest reliability (intraclass correlation coefficient = 0.99). GM‐FR scores discriminated between GMFCS levels (p < 0.05) and were strongly negatively correlated with GMFCS level (r = −0.92; p < 0.001). GM‐FR scores correlated positively and strongly with the Gross Motor Function Measure‐66 (r = 0.94; p < 0.001) and the Pediatric Evaluation of Disability Inventory – Computer Adaptive Test mobility domain (r = 0.93; p < 0.001).InterpretationActive participation of families in the GM‐FR's development facilitated creation of a family‐friendly instrument. This study provides strong evidence of reliability and validity to support GM‐FR use in clinical practice and research for assessing gross motor performance of children and adolescents with CP.