Reliability of Greek version Gross Motor Function Classification System

The Gross Motor Function Classification System for Cerebral Palsy (GMFCS), a reliable and valid system, has been widely utilized for objective classification of the patterns of motor disability in children with cerebral palsy. The objective of this study was to produce a Greek version of the instrument, with the same construct as the original one and to investigate the reliability of application of the Greek version GMFCS. Translation and back translation was made by two of the authors, one of whom did not know the original English text. The final translation was fixed by consensus. Two physicians were trained and given practice in the use of the GMFCS and its application to clinical documentation. The raters classified children with cerebral palsy according to GMFCS - Greek version. The reliability was assessed with the weighted kappa statistic. The sample consisted of 47 boys and 47 girls, mean age 5.4 years. The overall weighted Kappa was 0.80 (95% CI=0.67-0.94). Weighted Kappa for level I was 0.91 (95% CI=0.74-1.09), for level II, 0.78 (95% CI=0.62-0.95), for level III, 0.85 (95% CI=0.68-1.02), for level IV, 0.85 (95% CI=0.67-1.03) and for level V, 0.84 (95% CI=0.66-1.03). The inter-rater reliability was lowest at level II. Percent agreement was 75%. Results of this study suggest that GMFCS - Greek version can be used reliably to classify patients with CP from clinical documentation. These results further support use of the GMFCS in clinical settings and for research. Investigation is needed to further assess the reliability and to determine the validity of the Greek version of the GMFCS.