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GMFM: Gross Motor Function Measure, Part I Kathy McKellar, “Knowledge Broker” January 2007 Based on a presentation by Dianne Russell, CanChild Centre for.

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Presentation on theme: "GMFM: Gross Motor Function Measure, Part I Kathy McKellar, “Knowledge Broker” January 2007 Based on a presentation by Dianne Russell, CanChild Centre for."— Presentation transcript:

1 GMFM: Gross Motor Function Measure, Part I Kathy McKellar, “Knowledge Broker” January 2007 Based 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 GMFM Motor Growth Curves (MCG’s): prognosis, treatment planning

3 Health Condition ( disorder/disease ) Interaction of Concepts ICF 2001 Environmental Factors Personal Factors Body function&structure (Impairment ) Activities(Limitation)Participation(Restriction)

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 GMFM Criterion-referenced test: evaluates performance of motor skills on that day; useful for comparison over time Measures 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 yrs May be appropriate for children with other diagnoses GMFM 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’s Before testing children, PT’s should familiarize themselves with the scoresheet and the administration and scoring guidelines CD ROM training available

9 Time required GMFM 88: approx 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 items in 5 gross motor dimensions (for ease of administration): lying and rolling crawling and kneeling Sitting Standing walking, running and jumping

11 GMFM-66 Same dimensions, but 22 items eliminated (mostly in lying position)

12 Validation of the GMFM-88 Reliability Test-retest (ICC = 0.99) ( dimensions ranged ) Inter-rater (ICC = 0.99) (dimensions ranged ) Validity Gradient of change: pre-school children without CP>children with ABI>children with CP Children 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 Discriminative validity (Palisano et al 2000)

15 Why use the GMFM? Reliable, valid Internationally accepted: Translated into several languages, including Dutch, French, German, Icelandic, Japanese Considered best practice Used as an outcome measure

16 Surgery (rhizotomy, pallidal stimulation, muscle tendon) Drugs (botulinum toxin, intrathecal baclofen) Physical therapy (including ambulatory aids & orthoses) Horseback riding Strength 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 Equipment GMFM kit Need smooth floor, large firm exercise mat, toys for motivation, large bench or table for cruising Five steps with railing Wheeled stool

20 Environment Room large enough to accommodate the equipment, the child and the examiner Private area Consistent environment for retesting

21 Clothing Shorts and Tshirt are ideal Testing 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 Testing Items may be tested in any order, but be careful not to miss any! (esp. when using the GMFM 88) Verbal encouragement or demonstration is permitted Maximum 3 trials for each item Spontaneous performance of any item is acceptable

24 Non-compliance Strategies such as “follow the leader” or role playing can be used Toys 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 trials If undecided about what score to assign, choose the lower of the 2 possible scores Any item that has been omitted or that the child is unable (or unwilling) to attempt must be indicated as NT In the GMFM 88, NT items are scored 0, but in the GMFM 66, NT items are treated as missing data

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29 GMFM Part II… to follow GMFM-88 vs. 66 Scoring GMAE Interpretation of results Motor Growth Curves GMFCS, GMFM, MCG’s: how do they relate?

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31 Knowledge Broker study CanChild research project looking at clinical knowledge and appropriate use of: GMFCS GMFM Motor Growth Curves (MCG’s)

32 GMFM Part II Quick review Scoring GMAE Interpretation of results GMFM-88 vs. 66 Motor Growth Curves GMFCS, GMFM, MCG’s: how do they relate?

33 GMFM Criterion-referenced test: evaluates performance of motor skills on that day; useful for comparison over time Measures 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 yrs May be appropriate for children with other diagnoses: osteogenesis imperfecta, lymphoblastic leukemia, Down syndrome GMFM is appropriate for children whose motor skills are at or below those of a typical 5 year old.

35 GMFM- 88 and 66 GMFM 88: 88 items in 5 gross motor dimensions: lying and rolling crawling and kneeling Sitting Standing walking, running and jumping GMFM-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 only First complete the GMFM without the aid/orthosis, then retest with aid/orthosis For repeat testing at a later dater, apply the same aid at the same item number Aids/orthoses could have positive and negative effects Mark 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 % scores Change scores: T2 - T1 = GMFM  score Assumes 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 scale Really need ‘interval’ scaling, whereby a ‘unit’ of change has the same meaning throughout the scale Hence 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 difficulty Interval 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 tutorial Allows entry of data in two formats: 1. Research - from ASCII files or text only files (files entered into a statistical package –SPSS) 2. 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 administered  Provides a database to keep child information and track GMFM-66 scores over time- case summary report  Produces item maps- arrange items by order of difficulty  It’s easy! No math, but graphs!

46 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. What is the GMFM-66 score?

47 Case Summary Report Summarizes demographic data Summarizes score, including error (standard error and 95% confidence interval) Graphs scores over time

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49 Item Maps By item order or by difficulty order- by difficulty order is the most useful

50 Appendix 3 figure A3.3 Item Map by Difficulty OrderGross Motor Function Measure GMFM-66 Client ID:3 Name:Susie Q Assessment Date:03 April 1989GMFM-66 Score:41.61 Date of Birth:07 July 1987Standard Error:1.14 Age: 1y 8m95% Confidence Interval:39.38to43.84 More Difficult Lower Motor GMFM-66 Score with 95% Confidence Intervals Higher Motor Ability Ability

51 Clinical Use of Item Maps and Case Summaries understand/interpret change identify relatively easier and more difficult ‘next steps’ for a child discuss and communicate a child’s progress set 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 66 Good 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 attempted If administer the GMFM-88 with NT, the data can also be used to calculate score for GMFM- 66

56 Strengths of GMFM-88 Reliable and valid measure of change over time in children with CP and children with Down syndrome Widely used in practice and research GMFM 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 administered Must give a score of “0” for items if the child refuses or assessor fails to administer Score 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 computer Assessing effects of aides and orthoses Assessing children with diagnosis other than CP

59 Strengths of GMFM-66 Reliable and valid measure of change over time in children with CP Items are ordered by difficulty A score can be derived with a less-than- complete assessment Item maps useful in understanding motor function and in planning goals Computer program allows tracking of individual children’s scores over time

60 Possible Limitations of GMFM-66 Requires use of a computer program for scoring May need some time to learn how to interpret item maps No 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 items Access to a computer and the GMAE scoring program

62 Motor Growth Curves More graphs!

63 Motor Growth Curves Derived from a longitudinal study 657 children, >2600 GMFM assessments Children <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 time Estimate 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) evaluative prognostic (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

68 Case Study Beth

69 Use of Motor Measures at QA How could these measures work for us? *** Most useful if used by all PT’s, in both EIP and SAP


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