Reliability and validity of the Dutch-language version of the Viking Speech Scale

Abstract

Title Reliability and validity of the Dutch-language version of the Viking Speech Scale. Background Children with cerebral palsy (CP) are classified using functional classification systems. The Viking Speech Scale (VSS) is used to classify speech. A Dutch-language version is not yet available. Aim To determine the reliability and validity of the Dutch-language version of the VSS (VSS-NL) and the association of VSS-NL-level with motor type of CP and with the functional profiles for gross motor-, communication-, and manual functioning. Method A prospective, cross-sectional, observational study was conducted. Fifty-five children with CP (32 males, mean age 6;3 years, SD 1;6 years) participated. VSS-NL Classification of the speech language therapist (SLT)1 (researcher), SLT2 (of the child), parent and physiatrist were compared. Convergent and discriminant validity was examined with the Intelligibility in Context Scale-Dutch (ICS-NL) and the Computer Based Instrument for Low Motor Language Testing (C-BiLLT). Inter- and intrarater reliability was determined by weighted Kappa. Validity, and associations with type of CP, Gross Motor Function Classification System (GMFCS), Manual Ability Classification System (MACS), Communication Function Classification System (CFCS), were determined with Spearman’s coefficient. Results Excellent interrater agreement between SLT1 and SLT2 (k=0.926), good for SLT1-parent, (k=0.669), SLT1-physiatrist, SLT2-parent (k=0.707), SLT2-physiatrist, and parent-physiatrist (k=0.729). Intrarater agreement was excellent for SLTs1-SLTs2 (k=1.000), very good for physiatrists (k=0.891) and good for parents (k=0.783). Convergent validity was strong (r=-0.745), and discriminant validity moderate (r=-0.484). We found moderate associations with motor type of CP (r=0.467), GMFCS (r=0.537), CFCS (r=0.572) and MACS (r=0.500). Conclusion The VSS-NL is a reliable and valid system to classify the speech performance of children with CP (≥ 4 years), and classifications can be reliably performed by SLTs, parents and physiatrists.

Recommendations Implementation of the VSS-NL in the Netherlands to classify the speech performance of children with CP.