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RehabMeasures

Functional Mobility Scale

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Purpose

The FMS classifies the functional mobility of children 4-18 years of age with cerebral palsy, taking into account the assistive devices a child might use.

Link to Instrument

Instrument Details

Acronym FMS

Cost

Free

Populations

Key Descriptions

  • 3 items (distances), each of which is rated from 1-6 depending on assistance required, or “C” for crawling or “N” if distance is not completed
  • Maximum score is a 6 for each of the distances (5m, 50m, and 500m)
  • For each of three distances (5m, 50m, and 500m), a rating of 1-6 is assigned depending on the assistance required. 1 = uses wheelchair, 2 = uses a walker or frame, 3 = uses crutches, 4 = uses sticks (one or two), 5 = independent on LEVEL surfaces, 6 = independent on ALL surfaces, “C” = crawling (for mobility at home), “N” = does not apply [e.g., child does not complete the distance (500m)]
  • Assessment is not completed by direct observation of the clinician. The clinician asks the child/parent how the child moves around: 1) for short distances in the house (5m), 2) in and between classes at school (50m), and 3) for long distances such as at the shopping center (500m). Assessment is by the clinician based on child/parent responses to the questions asked by the clinician. The answers to the questions are based off what the child actually does at the point in time that the instrument is completed (performance), not what they can do or used to be able to do (capability). The walking ability is rated according to the need for assistive devices, such as crutches, walkers, or wheelchair, for each of the distances

Number of Items

3 distances

Equipment Required

  • Pen or Pencil
  • Functional Mobility Scale Form

Time to Administer

5-10 minutes

Required Training

No Training

Instrument Reviewers

Lynette Reina, PT, DPT; reviewed by Ada Terman March, 2019.

Considerations

  • The Functional Mobility Scale is available in multiple languages including:  English, Japanese, Chinese, Dutch, French, Portuguese, Spanish, Swedish, Thai.
  • Specific questions to ask are not provided on the original Functional Mobility Scale tool, therefore increasing variability in how questions are delivered to the parents/child by the clinician.
  • The Functional Mobility Scale is intended to assess performance (what a child does) rather than capability (what a child can do).
  • Functional Mobility Scale – Rett Syndrome (FMS-RS) has been modified from the FMS. The FMS-RS assesses walking performance over the 5m, 50m, and 500m corresponding to home ambulation, day center ambulation, and community ambulation.  The scoring system ranges from a 0-4 for each distance (“0” = unable; “4” = independent).  (Stahlhut et al., 2016)

Cerebral Palsy

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Interrater/Intrarater Reliability

Inter-rater Reliability:

Cerebral Palsy: (Graham et al., 2004; n=310, n (spastic hemiplegia) = 114, n (spastic diplegia) = 124, n (spastic quadriplegia) = 72; mean age = 11 (3.7), mean age (spastic hemiplegia) = 12 (3.6), mean age (spastic diplegia) = 12 (4.0), mean age (spastic quadriplegia) = 10 (3.7))

  • Excellent inter-rater reliability for the three distances (5m, 50m, and 500m) between attending surgeon and research fellow

Intraclass Correlation Coefficient (ICC), Cronbach’s α, and Concordance Correlation Coefficient (CCC) (95% confidence intervals) Between Attending Surgeon and Research Fellow

 

ICC

Chronbach’s α

CCC

FMS-5

0.95* (0.88-0.98)

0.95* (0.86-0.98)

0.97* (0.94-0.99)

FMS-50

0.94* (0.88-0.97)

0.94* (0.87-0.99)

0.96* (0.93-0.99)

FMS-500

0.95* (0.89-0.99)

0.96* (0.89-0.99)

0.98* (0.93-0.99)

*indicates “Excellent”

 Cerebral Palsy: (Harvey et al., 2010; n (total) = 118, n (2-6 year) = 16, n (6-12 years) = 66, n (12-18 years) = 36, n (GMFCS I) = 13, n(GMFCS II) = 49, n(GMFCS III) = 44, n(GMFCS IV) = 12; mean age (SD) = 10.3 (3.6); raters = hospital physiotherapist, community physiotherapist, and surgeon)

  • Excellent correlations for independent ratings of mobility for the three distances (Kappa (95% Confidence Interval (CI)) and agreement (%):  5m = 0.87(0.74, 0.99) and 96%; 50m = 0.92(0.74, 1.00) and 98%; 500m = 0.86(0.68, 1.00) and 96%)
  • Adequate to Excellent correlations for independent ratings for mobility for the three distances by age group

Kappa Coefficients and 95% Confidence Intervals for Independent Ratings of Mobility for the Three Distances by Age Group

Age

Distance

Kappa (CI)

Agreement (%)

2-6 years (n=16)

5m

0.87* (0.47, 1.00)

93*

 

50m

0.95* (0.47, 1.00)

99*

 

500m

0.64** (0.20, 1.00)

92*

6-12 years (n=66)

5m

0.86* (0.68, 1.00)

96*

 

50m

0.90* (0.66, 1.00)

98*

 

500m

0.89* (0.65, 1.00)

96*

12-18 years (n=36)

5m

0.83* (0.58, 1.00)

96*

 

50m

0.94* (0.61, 1.00)

99*

 

500m

0.86* (0.54, 1.00)

96*

*Indicates “Excellent”

**Indicates “Adequate”

 Intra-rater Reliability:

Cerebral Palsy:  (Himuro et al., 2017; n (all participants) = 24, mean age 13 (2 y 4 mo); n=18 (spastic unilateral), n=3 (spastic bilateral), n=2 (dyskinetic), n=1 (ataxic); n (GMFCS level I) = 11, n (GMFCS level II) = 8, n (GMFCS level III) = 5; Japanese version rated twice with a 1-2 week interval between assessments)

  • Adequate correlations for the independence ratings of mobility for the 5m (Kappa (95% CI) and agreement (%): 0.72(0.45, 0.99) and 83% agreement)
  • Excellent correlations for the independence ratings of mobility for the 50m (Kappa (95% CI) and agreement (%): 0.87(0.68, 1.00) and 92% agreement)
  • Excellent correlations for the independence ratings of mobility for the 500 m (Kappa (95% CI) and agreement (%): 0.76 (0.53, 0.99) and 83% agreement)

Internal Consistency

Cerebral Palsy: (Graham et al., 2004)

  • Excellent internal consistency for the FMS-5 (Chronbach’s α= 0.95)
  • Excellent internal consistency for the FMS-50 (Chronbach’s α= 0.94)
  • Excellent internal consistency for the FMS-500 (Chronbach’s α= 0.96)

Criterion Validity (Predictive/Concurrent)

Concurrent validity:

Cerebral Palsy:  (Graham et al., 2004)

  • Excellent correlation of the FMS with the PODCI (Pediatric Outcomes Data Collection Instrument), CHQ (Child Health Questionnaire), and Uptime
  • Excellent correlation of the FMS with Rancho Scale
  • Adequate correlation of the FMS with energy expenditure

Spearman Correlation Coefficient Matrix Between FMS-5, FMS-50, and FMS 500 and PODCI, CHQ, and Uptime (UT)

 

FMS – 5

FMS – 50

FMS – 500

PODCI

CHQ

E

RS

UT

FMS – 5

1.00

 

 

0.89*

0.78*

0.51***††

0.78*

0.87*

FMS – 50

 

1.00

 

0.84*

0.82*

0.52***††

0.72*

0.83*

FMS – 500

 

 

1.00

0.82*

0.81*

0.55***††

0.71*

0.84*

PODCI

 

 

 

1.00

0.75**

0.53††

0.80***

0.79*

CHQ

 

 

 

 

1.00

0.54††

0.74***

0.81*

E

 

 

 

 

 

1.00

0.54***††

0.61

RS

 

 

 

 

 

 

1.00

0.78**

UT

 

 

 

 

 

 

 

1.00

*p<0.001

**p<0.01

*** p<0.05

Indicates “Excellent”

†† Indicates “Adequate”

 Cerebral Palsy: (Himuro et al., 2017; n (all participants) = 111, n (GMFCS level I) = 64, n (GMFCS level II) = 29, n (GMFCS level III) = 18; mean age (all participants) = 12 y 1 mo (± 3 y 7 mo), mean age (GMFCS level I) = 12 y 3 mo (3 y 8 mo), mean age (GMFCS level II) = 11 y 4 mo (3 y 7 mo), mean age (GMFCS level III) = 12 y 8 mo (3 y 2 mo); Japanese sample)

  • Excellent correlation of Gross Motor Function Classification System (GMFCS) for the three distances in the FMS:  FMS – 5m = -0.71; FMS – 50m = -0.73; FMS – 500m = -0.75 (correlation with p<0.01)

Predictive validity:

Cerebral Palsy:  (Wilson et al, 2014; n (all participants) = 143, n (GMFCS level I) = 44, n (GMFCS level II) = 75, n (GMFCS level III) = 24; mean age = 10.6 (3.2)

  • 6MWT (6 Minute Walk Test) is a major independent predictor in the model for each FMS distance, with clear discrimination between parent-reported FMS scores of 5 versus 6 at all three FMS distances
  • WS (walking speed) is a minor contributor to the predictive value for the FMS
  • Topography of cerebral palsy contributed to predictive value at FMS 50 and 500, but not at FMS 5

Multiple Ordinal Logistic Regression Analysis

 

FMS 5

FMS 50

FMS 500

 

Step 1

Step 2

Step 3

Step 1

Step 2

Step 3

Step 1

Step 2

Step 3

R2

0.27

0.32

Not add-itional

0.20

0.22

0.24

0.22

0.26

0.28

 

 

 

 

 

 

 

 

 

6MWT

P<.001

P<.001

 

P<.0001

P<.0001

P<.001

P<.0001

P<.0001

P<.0001

WS

 

P<.001

 

 

P=.01

P=.006

 

P<.0001

P=.008

Unilateral vs bilateral

 

 

 

 

 

P=.04

 

 

P<.001

Step 1 = 6MWT

Step 2 = 6MWT and WS

Step 3 = 6MWT, WS, and Unilateral vs bilateral spasticity

 

Construct Validity

Convergent validity:

Cerebral Palsy (spastic diplegia):  (Graham et al., 2004; n= 35 (subsample of original study population who underwent surgical intervention); mean age = 10.3 (2.3))

  • Excellent ability to demonstrate difference between pre- and postoperative state and to detect improvement and decline in walking ability during rehabilitation.
  • Excellent correlation for the FMS with Uptime (UT)
  • Excellent correlation for the FMS with physical functioning domains of the PODCI
  • Excellent correlation for the FMS with the Child Health Questionnaire (CHQ)
  • Adequate correlation for the FMS with energy expenditure as measured by oxygen cost (E)

 

Spearman Correlation Coefficient for Change in Ratings Between FMS-5, FMS-50, and FMS 500 and Other Outcome Tools at 6 and 12 Months Postoperatively (n=35, spastic diplegia)

 

PODCI

CHQ

E

UT

6 months

FMS – 5

0.78*†

0.77**†

0.53*††

0.86**†

FMS – 50

0.82*†

0.80*†

0.59*††

0.84**†

FMS – 500

0.81**†

0.80**†

0.52*††

0.85**†

PODCI

1.00

0.78***†

0.51*††

0.81**†

CHQ

 

1.00

0.53*††

0.82**†

UT

 

 

1.00

1.00

12 months

FMS – 5

0.79*†

0.75**†

0.54*††

0.78**†

FMS – 50

0.81**†

0.82*†

0.55*††

0.85**†

FMS – 500

0.80**†

0.83**†

0.53*††

0.89**†

PODCI

1.00

0.81***†

0.55*††

0.84**†

CHQ

 

1.00

0.56*††

0.81**†

UT

 

 

1.00

1.00

 

*p<0.05

**p<0.01

***p<0.01

† Indicates “Excellent”

†† Indicates “Adequate”

 Cerebral Palsy (spastic): (Harvey et al, 2009; n (all participants) = 18, n (GMFCS level II) = 5, n (GMFCS level III) = 4, n (GMFCS level IV) = 9; mean age = 12 y 8 mo (±2y 8 mo); n (spastic quadriplegia) = 9, n (spastic diplegia) = 7, n (spastic hemiplegia) = 2)

  • Excellent agreement was found between FMS parent-reported ratings and direct observation for all three distances (Kappa(95% CI) and agreement (%):  FMS 5m = 0.71 (0.41, 1.00) and 45%; FMS 50m = 0.76 (0.31, 1.00) and 94%; FMS 500m = 0.74 (0.33, 1.00) and 95%)

Content Validity

Cerebral Palsy:  (Graham et al., 2004)

  • FMS differentiated children with varying degrees of walking ability that would typically be grouped under the same functional category using the Rancho Scale (RS).  All children with spastic hemiplegia were rated as community ambulators through the RS; however, some of these children scored a 4 on the FMS-500 scale.  This indicated occasional need for assistive devices (AD).
  • Of the children with spastic diplegia rated as community ambulators on the RS, 24% required use of AD at 500m, 13% at 50m, and 5% at 5m. 
  • Of the children with spastic quadriplegia rated as non-ambulators on the RS, all required wheelchairs at 500m, 77% required wheelchairs at 50m, and 69% required wheelchairs at 5m

Responsiveness

Cerebral Palsy: (Harvey et al., 2007; n (all participants) = 66, n (GMFCS level I) = 18, n (GMFCS level II) = 24, n (GMFCS level III) = 24; mean age = 10 (2y 6mo); average procedures per child = 8 (range of 4-12 procedures)

  • Excellent responsiveness at 3 mo postoperative, 6 mo postoperative, and 24 mo postoperative.  FMS showed decline immediately post-op then improved over 24 mo

Odds ratios (OR) for FMS distances for post-operative time period compared with baseline (preoperatively)

Time post-op

5m

   

50m

   

500m

   
 

OR

CI

p value

OR

CI

p value

OR

CI

p value

3 mo

0.13*

0.07-0.24

<0.001

0.09*

0.04-0.17

<0.001

0.24**

0.14-0.43

<0.001

6 mo

0.36**

0.23-0.58

<0.001

0.32**

0.19-0.55

<0.001

0.50**

0.32-0.80

0.004

9 mo

0.69**

0.45-1.04

0.08

0.77**

0.49-1.19

0.24

0.90***

0.57-1.41

0.628

12 mo

1.12***

0.77-1.64

0.55

1.22***

0.82-1.81

0.33

1.47***

0.97-2.22

0.071

24 mo

2.08***

1.33-3.24

0.002

2.16***

1.37-3.41

0.001

2.23***

1.44-3.45

<0.001

CI – Confidence Interval

*Indicates “Small change”

**Indicates “Moderate change”

***Indicates “Large change”

Bibliography

Graham, H.K., Harvey, A., et al. (2004).  “The Functional Mobility Scale (FMS).”  Journal of Orthopaedics 24(5):  514-520. 

Harvey, A., Baker, R., et al. (2009).  “Does parent report measure performance?  A study of the construct validity of the Functional Mobility Scale.” Developmental Medicine & Child Neurology 52: 181-185.

Harvey, A., Graham, H.K., et al. (2007).  “The Functional Mobility Scale:  ability to detect change following single event multilevel surgery.” Developmental Medicine & Child Neurology 49:  603-603.

Harvey, A.R., Morris, M.E., et al. (2010). “Reliability of the Functional Mobility Scale for children with cerebral palsy.”  Physical & Occupational Therapy in Pediatrics 30(2):  139-149.

Himuro, N., Nishibu, H., et al. (2017). “The criterion validity and inter-rater reliability of the Japanese version of the Functional Mobility Scale in children with cerebral palsy.” Research in Developmental Disabilities 68: 20-26.

Stahlhut, M., Downs, J., et al. (2016). “Building the repertoire of measures of walking in Rett syndrome.” Disability and Rehabilitation 39(19): 1926-1931.

The Royal Children’s Hospital. (2014). FMS: The Functional Mobility Scale (version 2) – For children with cerebral palsy ages 4-18 years.   Retrieved from https://www.schn.health.nsw.gov.au/files/attachments/the_functional_mobility_scale_version_2.pdf

Wilson, N.C., Mackey, A.H., et al. (2014). “How does the Functional Mobility Scale relate to capacity-based measures of walking ability in children and youth with cerebral palsy?” Physical & Occupational Therapy in Pediatrics 34(2): 185-196.

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