The Interrater Reliability of the Greek Expanded and Revised Gross Motor Function Classification System and the Family Report Questionnaire in Cerebral Palsy

Abstract

Background/Objectives: The Gross Motor Function Classification System–Expanded Revised (GMFCS-E R) is widely used to describe gross motor performance in children with cerebral palsy (CP). Although Greek-language materials are available, interrater reliability across healthcare professionals and parents has not been examined. This study evaluated the reliability of the Greek GMFCS-E R among a pediatric neurologist, a pediatric physiotherapist, and parents, with an emphasis on descriptors and illustrations for older children and adolescents. Methods: A cross-sectional study was conducted with 111 children and adolescents with CP aged 2–18 years. Professionals classified each child using the Greek GMFCS-E R brochure (ages 2–6) or the descriptors and illustrations (ages 6–12 and 12–18). Parents completed the age-appropriate GMFCS Family Report Questionnaire. Agreement among the three raters was assessed using Fleiss’ kappa (κF), and pairwise agreement using weighted Cohen’s kappa (κCw), overall and by age band. Results: Overall interrater reliability was substantial (κF = 0.77). Agreement by GMFCS level ranged from κF = 0.68 (Level V) to κF = 0.85 (Level I). Reliability increased with age, reaching κF = 0.74–0.85 in adolescents. Pairwise agreement was excellent across all rater pairs, with near-perfect concordance between the pediatric neurologist and physiotherapist (κCw = 0.98). In 60% of disagreements, parents assigned higher levels, typically between adjacent categories. Conclusions: The Greek-language GMFCS-E R demonstrates high interrater reliability among healthcare professionals and parents, with excellent agreement when using descriptors and illustrations for older children and adolescents. The GMFCS-FR effectively incorporates parental perspectives and complements clinical assessment, supporting the use of the Greek GMFCS-E R in routine clinical practice and research settings.

Key findings

• ▸Overall interrater reliability was substantial with a Fleiss' kappa coefficient of 0.77.
• ▸Agreement ranged from moderate to substantial across levels, specifically from κF = 0.68 for Level V to κF = 0.85 for Level I.
• ▸The study successfully validated the use of Greek-language descriptors and illustrations for classifying motor function in older children and adolescents.

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Identifiers

DOI

10.3390/children13030368

Journal

Children

Year

2026