Intra- and interrater reliability of the Modified Ashworth Scale and its association with the Tardieu Scale in children with cerebral palsy

Background The Modified Ashworth Scale is a widely used tool for assessing spasticity. The aim of this study was to evaluate the intra- and interrater reliability of the Modified Ashworth Scale and its association with the Tardieu Scale in children with cerebral palsy. Methods In this cross-sectional study, 23 children with cerebral palsy were included. The intra- and interrater reliability of the Modified Ashworth Scale was assessed for the elbow, knee, and plantar flexors of the foot. The results of the Tardieu Scale were included to evaluate the association between the two scales. The intraclass correlation coefficient (ICC) was used to assess reliability, and Spearman’s correlation coefficient was used to assess the association between the Modified Ashworth Scale and the Tardieu Scale. All muscles assessed were included in the analysis, regardless of the anatomical classification of physical impairment. Results Intrarater reliability (ICC) in our sample was excellent for all muscles assessed (ICC = 0.91–0.99). Interrater reliability was generally good, with confidence intervals indicating moderate to good reliability in certain muscle groups (ICC = 0.80–0.89). A moderate positive correlation was observed between the Tardieu Scale and the Modified Ashworth Scale for all muscles assessed. Conclusions The results demonstrated excellent intrarater and generally good interrater reliability in a heterogeneous primary healthcare sample, with a moderate positive correlation between the scales studied. However, caution is warranted when interpreting findings at the individual level.