Reliability and Construct Validity of the Communication Function Classification System (CFCS) in an Italian Population of Children with Cerebral Palsy

<b>Background/objectives:</b> Communication difficulties are highly prevalent among children with cerebral palsy (CP) and have a significant impact on participation, psychosocial development, and quality of life. The Communication Function Classification System (CFCS) was developed to provide a standardized framework for describing functional communication performance across five ordinal levels. While the CFCS has been validated internationally, evidence on its psychometric properties in Italian pediatric populations remains limited. The objective of this study was to examine the inter-rater and intra-rater reliability of the Italian version of the CFCS and to explore construct validity through a single association with the Gross Motor Function Classification System Expanded and Revised (GMFCS E&R). <b>Methods</b>: A cross-sectional study was conducted with 66 children with CP (mean age 8.8 years, SD = 4.9) recruited from the Bambino Gesù Children's Hospital in Rome. Two trained raters independently classified each child using the CFCS and GMFCS E&R, with CFCS reassessments performed after 14-20 days to evaluate intra-rater stability. Agreement was assessed using linear weighted Cohen's Kappa (κᵂ) coefficients, and construct validity was analyzed using Spearman rho correlation (r) between CFCS and GMFCS E&R levels. <b>Results</b>: The CFCS demonstrated almost very good agreement for both inter-rater and intra-rater reliability, with κᵂ values exceeding 0.90. Construct validity was supported by a strong and statistically significant correlation with GMFCS E&R (r = 0.82, <i>p</i> < 0.01), indicating that greater motor impairment was associated with more severe communication limitations. <b>Conclusions</b>: The Italian version of the CFCS is a highly reliable classification system and shows evidence of construct validity based on a single convergent association in children with CP. These findings support its use for descriptive and classificatory purposes in clinical and research contexts, while further studies are needed to examine additional psychometric properties.