Age-related reference values for the SARA in children; – A European multicenter study

Abstract

Objectives: Reliable ataxia biomarkers are crucial for the assessment of ataxia severity in Early Onset Ataxia (EOA). The Scale for Assessment and Rating of Ataxia (SARA) was originally designed as a quick and easily applicable tool for the quantification of ataxia in adults. However, due to the favorable characteristics, the SARA is increasingly being applied in children. Before SARA-scores can be analogously interpreted in children and adults, the influence by phenotypic and genotypic differences should be taken into account, first. In the present study, the Childhood Ataxia and Cerebellar Group of the European Paediatric Neurology Society (CACG-EPNS) aimed to validate SARA-scores according to age. Methods: In 156 healthy children, from nine different European countries, (n=12/year; m:f=1:1; age range 4–16 years), twenty-two paediatric neurologists (CACG-EPNS members) independently scored SARA according to official SARA guidelines. We subsequently determined international inter-observer agreement and the association between SARA-scores and age for age-related reference values. Results: In healthy children, the international inter-observer agreement of SARA-scores was substantial (Intraclass Correlation Coefficient: 0.69). SARA- scores were associated with age (R2=0.47). The youngest children revealed the highest scores and also the highest variation in scores (<8 years; p<.001). Within the age range from 4 to 16 years of age, median outcomes declined from 5 to 0 (ranges 1.5 – 7.0 and 0 – 1.0, respectively). At 12 years of age, SARA-scores had reached the adult optimum (median 0 (ranges 0 – 1.0)). Conclusion: In healthy European children, both SARA-scores and inter- observer agreement are age-dependent. For reliable interpretation of paediatric SARA-scores, consideration of the underlying test construct appears prudent. These data may hopefully contribute to optimal interpretation of longitudinal SARA-scores from childhood to adulthood.