Presentation on theme: "GMFM: Gross Motor Function Measure, Part I"— Presentation transcript:
1 GMFM: Gross Motor Function Measure, Part I Kathy McKellar, “Knowledge Broker”January 2007Based on a presentation by Dianne Russell, CanChild Centre for Childhood Disability Research, Knowledge Broker project co-investigator
2 KB study Looking at clinical knowledge and appropriate use of: GMFCS GMFMMotor Growth Curves (MCG’s): prognosis, treatment planning
4 GMFM: Why was it developed? To answer the question: “How do we measure small but important changes in motor function for children with CP?”Development started in 1984
5 GMFMCriterion-referenced test: evaluates performance of motor skills on that day; useful for comparison over timeMeasures how much of a task the child can accomplish, rather than how well the task is completed (quantity, not movement quality)
6 Who is the GMFM appropriate for? Children with CP: original validation sample included kids 5 mo- 16 yrsMay be appropriate for children with other diagnosesGMFM is appropriate for children whose motor skills are at or below those of a typical 5 year old.
7 GMFM Formats GMFM-88: 88 items GMFM-66: 66 items GMFM-88 with reported scores for kids with Down Syndrome
8 Examiner Qualifications For use by pediatric PT’sBefore testing children, PT’s should familiarize themselves with the scoresheet and the administration and scoring guidelinesCD ROM training available
9 Time required GMFM 88: approx. 45-60 minutes GMFM 66: faster, allows for some missing data (items that are not tested)Can be completed in more than 1 session (ideally complete all items within 1 week)
10 GMFM-8888 items in 5 gross motor dimensions (for ease of administration):lying and rollingcrawling and kneelingSittingStandingwalking, running and jumping
11 GMFM-66Same dimensions, but 22 items eliminated (mostly in lying position)
12 Validation of the GMFM-88 ReliabilityTest-retest (ICC = 0.99) ( dimensions ranged )Inter-rater (ICC = 0.99) (dimensions ranged )ValidityGradient of change: pre-school children without CP>children with ABI>children with CPChildren with CP who were young & mild > older & more severe
13 Validation of the GMFM-88 Change over 6 months as judged by parents, therapists, and a “masked” video analysis was correlated with change scores on the GMFM-88
14 Further evidence of reliability & validity Reliability established by others outside the GMFM team (Bjornson et al. 1994;1998, Nordmark et al. 1997)Responsiveness (Bjornson et al. 1998; Kolobe et al. 1998Discriminative validity (Palisano et al 2000)
15 Why use the GMFM? Reliable, valid Internationally accepted: Translated into several languages, including Dutch, French, German, Icelandic, JapaneseConsidered best practiceUsed as an outcome measure
16 Used as an outcome measure Surgery (rhizotomy, pallidal stimulation, muscle tendon)Drugs (botulinum toxin, intrathecal baclofen)Physical therapy (including ambulatory aids & orthoses)Horseback ridingStrength training & physical fitness
17 Use of the GMFM in other populations Osteogenesis imperfecta (Ruck-Gibis et al. 2001)Lymphoblastic leukemia (Wright et al. 1998)Down syndrome (Russell et al. 1998)
18 Validation for children with Down syndrome Compared the results using the standard scoring method with an alternate method of scoring using caregiver report “Reported Score” (for items which the therapist couldn’t entice the child to demonstrate)Found stronger evidence of reliability, validity & responsiveness with “reported score”
19 EquipmentGMFM kitNeed smooth floor, large firm exercise mat, toys for motivation, large bench or table for cruisingFive steps with railingWheeled stool
20 EnvironmentRoom large enough to accommodate the equipment, the child and the examinerPrivate areaConsistent environment for retesting
21 ClothingShorts and Tshirt are idealTesting is done without shoes
22 Preparing for Testing Have manual, equipment, score sheet ready. Room booked, mat in place, as well as other required furniture
23 TestingItems may be tested in any order, but be careful not to miss any! (esp. when using the GMFM 88)Verbal encouragement or demonstration is permittedMaximum 3 trials for each itemSpontaneous performance of any item is acceptable
24 Non-complianceStrategies such as “follow the leader” or role playing can be usedToys and incentives can be used as motivators (eg. creep through a tunnel)If a child refuses to attempt an item that you think they can do, return to the item at the end of the test, or try it again in in another session. You can also circle “not tested”.
25 Scoring the GMFM Scores 0-3 or NT 0- does not intitiate task 1- intitiates task (<10%)2- partially completes task (10-99 %)3- completes task (100%)Sometimes generic scoring as above, other times specific criteria for each level
26 Scoring the GMFM, cont.The score given is based on the best performance out of the 3 trialsIf undecided about what score to assign, choose the lower of the 2 possible scoresAny item that has been omitted or that the child is unable (or unwilling) to attempt must be indicated as NTIn the GMFM 88, NT items are scored 0, but in the GMFM 66, NT items are treated as missing data
31 Knowledge Broker study CanChild research project looking at clinical knowledge and appropriate use of:GMFCSGMFMMotor Growth Curves (MCG’s)
32 GMFM Part II Quick review Scoring GMAE Interpretation of results GMFM-88 vs. 66Motor Growth CurvesGMFCS, GMFM, MCG’s: how do they relate?
33 GMFMCriterion-referenced test: evaluates performance of motor skills on that day; useful for comparison over timeMeasures how much of a task the child can accomplish, rather than how well the task is completed (quantity, not movement quality)
34 Who is the GMFM appropriate for? Children with CP: original validation sample included kids 5 mo- 16 yrsMay be appropriate for children with other diagnoses: osteogenesis imperfecta, lymphoblastic leukemia, Down syndromeGMFM is appropriate for children whose motor skills are at or below those of a typical 5 year old.
35 GMFM- 88 and 66GMFM 88: 88 items in 5 gross motor dimensions:lying and rollingcrawling and kneelingSittingStandingwalking, running and jumpingGMFM-66: Same dimensions, but 22 items eliminated (mostly in lying position)
36 Scoring of the GMFM 88/66 Math or no math Graph or no graph Computer or no computer
37 GMFM-88 score: math!Sum the item scores within dimensions and transfer to the summary score section on the score sheet.A percent score for each of the 5 dimensions is calculated.The total percent score for each dimension is averaged to obtain the total score (round off to the nearest whole number)
38 Scoring with aids/orthotics Use GMFM-88 onlyFirst complete the GMFM without the aid/orthosis, then retest with aid/orthosisFor repeat testing at a later dater, apply the same aid at the same item numberAids/orthoses could have positive and negative effectsMark an “A” for the aided score on the score sheet
39 GMFM-88 - scoring issues (i) Scoring leads to an overall % score as well as dimension % scoresChange scores: T2 - T1 = GMFM scoreAssumes that all % changes/unit of time have the same meaning…...but we don’t really know what a ‘unit’ of change means clinically! (Some changes might be easier to attain than others)
40 GMFM-88 - scoring issues (ii) GMFM-88 scaling is ‘ordinal’ (ordered)Cannot assume that a unit of change has the same meaning across the scaleReally need ‘interval’ scaling, whereby a ‘unit’ of change has the same meaning throughout the scaleHence the need for Rasch (item-response) analysis
41 What is Rasch Analysis?It is a way to analyse data to assess the ‘fit’, order and relative difficulty of items that measure a construct (e.g., GMF)
42 RASCH SCALING OF THE GMFM Identified items which did not “fit” the unidimensional construct eliminated 22 items (GMFM-66)Items are now arranged in order of difficulty (empirical)Response options within items are weighted according to difficultyInterval scale…so that a unit of change has the same meaning across the scale (thus improving the interpretability of scores)
43 GMFM-66 Only 66 items administered (asterixed on score sheet) Enter scores into the computer program: Gross Motor Ability Estimator (GMAE)Not possible to calculate the score with pencil and paper
44 Gross Motor Ability Estimator (GMAE) User-friendly program to analyze GMFM-66 scores with a built-in tutorialAllows entry of data in two formats:Research - from ASCII files or text only files (files entered into a statistical package –SPSS)Individual GMFM-66 item scores for one or more children
45 Why use a computer program to score? Provides an estimate of a child’s score even when not all items have been administeredProvides a database to keep child information and track GMFM-66 scores over time- case summary reportProduces item maps- arrange items by order of difficultyIt’s easy! No math, but graphs!
46 What is the GMFM-66 score?The GMFM-66 score is an interval-level measure of function where subjects are placed on an ability continuum ranging from 0 (low motor ability) to 100 (high motor ability). Interval level scoring makes comparisons of change over time more meaningful because a difference of, for example, 10 points means the same whether the child is at the lower end or the upper end of the scale.
47 Case Summary Report Summarizes demographic data Summarizes score, including error (standard error and 95% confidence interval)Graphs scores over time
49 Item MapsBy item order or by difficulty order- by difficulty order is the most useful
50 Item Map by Difficulty Order Gross Motor Function Measure GMFM-66 Appendix 3 figure A3.3Item Map by Difficulty Order Gross Motor Function MeasureGMFM-66Client ID: 3Name: Susie QAssessment Date: 03 April 1989 GMFM-66 Score: 41.61Date of Birth: 07 July 1987 Standard Error: 1.14Age: 1y 8m 95% Confidence Interval: to 43.84More DifficultLower Motor GMFM-66 Score with 95% Confidence Intervals Higher MotorAbility Ability
51 Clinical Use of Item Maps and Case Summaries understand/interpret changeidentify relatively easier and more difficult ‘next steps’ for a childdiscuss and communicate a child’s progressset appropriate goals and plan interventions
52 Interpretation of GMAE print-outs Group exercise
53 Questions for groups: What is the child’s GMFM-66 score? Are there any unexpected scores?What would you expect the child to accomplish next?What activities might you work on in PT with this child?
54 GMFM 88 and 66Good reasons to choose one or the other.
55 GMFM-88 & GMFM-66 General Issues Items are administered and scored the same, with the exception of a new category of ‘Not Tested’ (NT) to differentiate a true “0” from an item not attemptedIf administer the GMFM-88 with NT, the data can also be used to calculate score for GMFM-66
56 Strengths of GMFM-88Reliable and valid measure of change over time in children with CP and children with Down syndromeWidely used in practice and researchGMFM is most responsive to change in children with CP under age 5 years
57 Limitations of GMFM-88 Time to administer - all items must be administeredMust give a score of “0” for items if the child refuses or assessor fails to administerScore based on number of items completed regardless of difficulty
58 When should I use the GMFM-88? For a more detailed description of skills especially for children whose skills are primarily in Lying and Rolling activities (e.g., infants, or children classified at GMFCS Level V)No access to a computerAssessing effects of aides and orthosesAssessing children with diagnosis other than CP
59 Strengths of GMFM-66Reliable and valid measure of change over time in children with CPItems are ordered by difficultyA score can be derived with a less-than-complete assessmentItem maps useful in understanding motor function and in planning goalsComputer program allows tracking of individual children’s scores over time
60 Possible Limitations of GMFM-66 Requires use of a computer program for scoringMay need some time to learn how to interpret item mapsNo longer able to calculate dimension scores
61 When should I use the GMFM-66? Assessing children with cerebral palsy where the interval properties of the scale are important (e.g. Research purposes, change over time)When you have limited time to administer all itemsAccess to a computer and the GMAE scoring program
63 Motor Growth Curves Derived from a longitudinal study 657 children, >2600 GMFM assessmentsChildren <6 years assessed every 6 mo., older children assessed every 9-12 mo.Plotted GMFM-66 score against age
64 Longitudinal Motor Growth Curves for Children with Cerebral Palsy by GMFCS Level Using GMFM-66 (N=2624 observations)
65 How can the Motor Growth Curves be used? Describe patterns of gross motor function for children with cerebral palsy over timeEstimate a child’s future motor capabilities (prognosis)Compare child’s GMFM-66 score with children in the sample of a similar age and severity
66 GMFM-66 plateau Does not mean therapy is not needed! Work on quality, functional goals, equipment needs, prevention of secondary problems.
67 Putting the measures all together….. Several different purposes :discriminative (descriptive)evaluativeprognostic (predictive)Can be used together to track and evaluate change over time and determine how the rate of change compares to children of similar abilities and ages