Concurrent Validity and Responsiveness of the Peabody Developmental Motor Scales - 2 in Infants and Children with Pompe Disease Undergoing Enzyme Replacement Therapy

Purpose: To examine the responsiveness of the PDMS-2 in children diagnosed with Pompe disease who had different levels of functional mobility. To examine the concurrent validity between the PDMS-2 and the Alberta Infant Motor Scale (AIMS), the Pediatric Evaluation of Disability Inventory (PEDI) and the Pompe PEDI (PPEDI) in children diagnosed with Pompe disease. Methods: A secondary analysis was completed of the Genzyme Corporation Pompe efficacy trials for Myozyme. The children were divided into two functional groups, independent ambulators (group 1), and children who required use of assistive devices to ambulate or were unable to ambulate (group 2). Results: A significant difference was present between the mean PDMS-2 subtest and Gross Motor Composite percentage scores at baseline and at week 52 when the whole group was combined. Responsiveness measured by the factor of Time and Function revealed Locomotion subtest statistically significant mean percentage change within both functional groups from baseline to week 52 and between groups at both time periods. No significant within group or between group differences were seen for the Stationary subtest. The Object Manipulation iii subtest demonstrated significant change within group one from baseline to week 52 and between the functional presentations at week 52.The age equivalent correlations between the PDMS-2 and AIMS indicate a good to excellent relationship for all subtests except the Object Manipulation subtest. A four-month range in age equivalent scores was necessary to achieve 100% agreement between the AIMS and the PDMS-2. Correlations between the PDMS-2, Locomotion and Stationary subtest and PPEDI for all age groups were in the moderate to good and good to excellent range. Non-significant correlations were found for the Reflex and Object Manipulation subtest. Conclusions: The PDMS-2 gross motor subtests were responsive to change in a heterogeneous group of children diagnosed with Pompe disease. Responsiveness concerns were identified in the Object Manipulation and Stationary subtest when the children were divided into two different functional groups. A stronger relationship was present between the PDMS-2 and AIMS age equivalent scores than the percentile scores. Motor capacity on the PDMS-2 reflects actual performance in the home and community environment as measured by the PPEDI. iv Dedication This doctoral dissertation is dedicated to my husband Troy and our children Aubrie and Georgina. Without their support and encouragement completion of this dissertation would not have been possible. I am also grateful for my mother, Myrna and for the many friends who have supported me …