Reliability and Stability of Cerebral Palsy Classification Scales for Individuals with STXBP1 Related Disorders and...

To determine the interrater reliability and stability of the Gross Motor Function Classification System (GMFCS), mini-Manual Ability Classification System (mini-MACS), Manual Ability Classification System (MACS), and Communication Function Classification System (CFCS) in individuals with STXBP1 -Related Disorder ( STXBP1 -RD) and SYNGAP1 -Related Disorder ( SYNGAP1 -RD).

Data were collected from 83 individuals with STXBP1 -RD (mean age = 9.8 years) and 101 individuals with SYNGAP1 -RD (mean age = 10.9 years). Two raters completed the GMFCS, MACS/MiniMACS, and CFCS assessments on the same day, and test-retest stability was evaluated for participants with two longitudinal assessments.

Interrater agreement varied from 73.8% to 77.3% for the STXBP1 -RD cohort and from 60.5% to 83.3% for the SYNGAP1 -RD cohort. Interrater reliability weighted kappa scores for the STXBP1 -RD cohort varied from 0.83 to 0.93 while the SYNGAP1 -RD cohort ranged from 0.66-0.81. Test-retest stability scores for the STXBP1 -RD group varied from 0.62 to 0.94 while the SYNGAP1 -RD group ranged from 0.38 to 0.78. Significant correlations were found between all assessment scales for both STXBP1 -RD (Kendall's Tau range from 0.25-0.42) and SYNGAP1 -RD (Kendall's Tau range from 0.19-0.45).

The GMFCS, MACS/MiniMACS, and CFCS demonstrate appropriate levels of interrater reliability and stability for individuals with STXBP1 -RD and SYNGAP1 -RD.

Classification tools are reliable and stable in individuals with STXBP1 -RD and SYNGAP1 -RD. Gross motor function is least affected for both conditions.Language function is most affected for both conditions.Correlations are decreased compared to children with cerebral palsy due to phenotype differences.