Improved Scaling of the Gross Motor Function Measure for Children With Cerebral Palsy: Evidence of Reliability and Validity

Abstract

Background and Purpose. This study examined the reliability, validity, and responsiveness to change of measurements obtained with a 66-item version of the Gross Motor Function Measure (GMFM-66) developed using Rasch analysis. Subjects and Methods. The validity of measurements obtained with the GMFM-66 was assessed by examining the hierarchy of items and the GMFM-66 scores for different groups of children from a stratified random community-based sample of 537 children with cerebral palsy (CP). A subset of 228 children who had been reassessed at 12 months was used to test the hypothesis that children who are young (Ͻ5 years of age) and have "mild" CP will demonstrate greater change in GMFM-66 scores than children who are older (Ն5 years of age) and whose CP is more severe. Data from an additional 19 children with CP who were assessed twice, one week apart, were used to examine test-retest reliability. Results. The overall changes in GMFM-66 scores over 12 months and a time ϫ severity ϫ age interaction supported our hypotheses. Test-retest reliability was high (intraclass correlation coefficientϭ.99). Conclusion and Discussion. This study demonstrated that the GMFM-66 has good psychometric properties. By providing a hierarchical structure and interval scaling, the GMFM-66 can provide a better understanding of motor development for children with CP than the 88 item GMFM and can improve the scoring and interpretation of data obtained with the GMFM. T he Gross Motor Function Measure (GMFM) is a criterion-referenced observational measure that was developed and validated to assess children with cerebral palsy (CP). 1 The original GMFM was modified in 1990 based on feedback from the clinicians involved in the validation study. Three items were added to the original 85-item measure in an effort to allow the skills tested by those items to be assessed bilaterally. Prior to re-establishing the reliability of the GMFM measurements with the 3 items added, administration and scoring guidelines were developed. The reliability of scores obtained with the 88-item GMFM was established with the revised guidelines using videotaped examples, and this reliability was sufficiently high to permit the revised guidelines to replace the original guidelines (intraclass correlation coefficient [ICC]ϭ.90). 2 Further evidence of the reliability of measurements obtained with the 88-item GMFM has been established by several investigators for its use with children with CP 3-5 and for children with Down syndrome. 6 The 88 items of the GMFM are measured by observation of the child and scored on a 4-point ordinal scale (0ϭdoes not initiate, 1ϭinitiates Ͻ10% of activity, 2ϭpartially completes 10% to Ͻ100% of activity, 3ϭcompletes activity). The items are weighted equally and grouped into 5 dimensions: (1) lying and rolling (17 items), (2) sitting (20 items), (3) crawling and kneeling (14 items), (4) standing (13 items), and (5) walking, running, jumping (24 items). By the age of 5 years, children without motor delays can generally accomplish all...

Exploring the comparative responsiveness of a core set of outcome measures in a school‐based conductive education programme

“…The GMFM-88 and PEDI Part II had medium effect sizes (SRMs > 0.60) for their sub-scores and total scores. As expected, the GMFM-66 (Russell et al . 2000), an interval scale with greater sensitivity to change than the GMFM-88, had a large effect size (SRM = 1.0).…”

“…1989). With the recent introduction of the reduced-item, interval scaled GMFM-66 (Russell et al . 2000), we subsequently were able to compute GMFM-66 scores using the Gross Motor Ability Estimator software (Russell et al .…”

“…The Gross Motor Function Measure (GMFM-88 and GMFM-66) (Russell et al . 1989;Russell et al . 2000;Russell et al .…”

Relationships among functional outcome measures used for assessing children with ambulatory CP

“…All subscales and measures selected for analysis were previously validated for use in English-speaking children with CP. 3,[7][8][9][10][11][12][13][14] Each data collection session consisted of administration of the FAQ, PedsQL, PODCI, WeeFIM, and GMFM Dimensions D (standing) and E (walking, running, and jumping). The 37 questions from Dimensions D and E of the GMFM are included on both the GMFM-88 and the more recent GMFM-66.…”

Development of the Oxford ankle foot questionnaire: finding out how children are affected by foot and ankle problems

“…However, there is little evidence for the effectiveness of some of these interventions which potentially leaves children prone to harm from ineffective treatments and wasting of health service and family resources. Evaluation is predominantly carried out by clinical assessment; for instance by physical examination of the range joint of movement, or utilizing clinical rating scales such as exist, for example, for clubfoot (Wainwright et al 2002), or standardized assessments such as the Gross Motor Function Measure (Russell et al 2000). Instrumented gait analysis has been used to study the biomechanics of human motion (Schwartz et al 2004) and recently there has been a focus on specifically modelling foot function during gait (Stebbins et al 2006).…”