Inter-rater Reliability of the K-GMFM-88 and the GMPM for Children with Cerebral Palsy

OBJECTIVE: To examine inter-rater reliability of the Korean version Gross Motor Function Measure (K-GMFM-88) and the Gross Motor Performance Measure (GMPM) based on the video clips. METHOD: We considered a sample of 39 children (28 boys and 11 girls; the mean age=3.50±1.23 years) with cerebral palsy (CP). Two pediatric physical therapists assessed the children based on video recordings. RESULTS: For the K-GMFM-88, the intraclass correlation coefficient (ICC(3, 1)) ranged from .978 to .995, and Spearman's correlation coefficient ranged from .916 to .997. For the GMPM, ICC(3, 1) ranged from .863 to .929, and Spearman's correlation coefficient ranged from .812 to .885. With the gross motor function classification system classified according to the functional level (GMFCS I-II vs. III-V), the ICCs were .982 and .994 for the K-GMFM-88 total score and .815 and .913 for the GMPM total score. There were good or high correlations between the subscales of the two measures (r=.762-.884). CONCLUSION: The K-GMFM-88 and GMPM are reliable tools for assessing the motor function of children with CP. These two methods are highly correlated, which adds more reliability on them. Thus, it is advisable to use K-GMFM-88 and GMPM for children with CP to assess gross motor function.