Comparison of two outcome measures for infants with cerebral palsy and infants with motor delays

Background and Purpose. The purpose of this study was to compare the Gross Motor Function Measure (GMFM) and the Peabody Developmental Gross Motor Scale (PDMS-GM) as measures of change in infants with cerebral palsy (CP) and infants with motor delays. We hypothesized that mean change scores would be greater for the GMFM than for the PDMS-GM. Subjects and Methods. Subjects were 42 infants with a mean adjusted age of 13.9 months (SD=6.1, range=4.2-24.2) Twenty-four infants had CP, and 18 infants had motor delays. The GMFM and the PDMS-GM were administered to the infants 3 times over a 6-month period. Raw scores were standardized for data analysis Data were analyzed using a 3-factor repeated-measures analysis of variance. Results. For the 6-month period, mean PDMS-GM age-equivalent scores increased 3.8 months and mean scaled scores increased 35 points for infants with motor delays compared with increased scores of 1.8 months and 13 points for infants with CP. Mean GMFM scores increased by 12.2% for infants with motor delays and by 4.2% for infants with CP. The diagnosis X time interaction was significant. Infants with motor delays had a greater change in motor development compared with the infants with CP. The hypothesis that the GMFM is more responsive to cl-lange than the PDMS-GM as not supported. Conclusion and Discussion. The findings suggest that the GMFM and the PDMS-GM are comparable in measuring change in infants with CP or motor delays. Implications for selection and use of either measure are discussed.