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

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. 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-88
88 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. 1998
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. Used as an outcome measure
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

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?

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:
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 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. 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 Maps
By 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 A3.3
Item Map by Difficulty Order Gross Motor Function Measure
GMFM-66
Client ID: 3
Name: Susie Q
Assessment Date: 03 April 1989 GMFM-66 Score: 41.61
Date of Birth: 07 July 1987 Standard Error: 1.14
Age: 1y 8m 95% Confidence Interval: to 43.84
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