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Rehab Measures: Patient Specific Functional Scale

Link to instrument

Measure can be found on the Transport Accident Commission's website (external link) 

Title of Assessment

Patient Specific Functional Scale 

Acronym

PSFS

Instrument Reviewer(s)

Initially reviewed by Krista Van Der Laan PT, DPT, OCS in 2010; Updated with references for chronic pain, knee dysfunction, and amputee populations by Leah Michelsen, SPT and Annmarie Walkosz, SPT in 2011;
Updated with references for joint replacement, spinal stenosis, and upper extremity musculoskeletal populations by Richard Fernandez, SPT and Matthew Currier, SPT in 4/2012.

Summary Date

4/4/2013 

Purpose

Used to assess functional ability to complete specific activities

Description

  • Patients rate their ability to complete an activity on a 11-point scale at a level experienced prior to injury or change in functional status
    • "0" represents “unable to perform”
    • "10" represents “able to perform at prior level”
  • Patients select a value that best describes  their current level of ability on each activity assessed

Area of Assessment

Activities of Daily Living 

Body Part

Neck; Back; Lower Extremity 

ICF Domain

Activity; Participation 

Domain

Motor 

Assessment Type

Patient Reported Outcomes 

Length of Test

05 Minutes or Less 

Time to Administer

<4 minutes

Number of Items

Not applicable 

Equipment Required

None

Training Required

None

Type of training required

No Training 

Cost

Free 

Actual Cost

Free: Measure can be found in:
Stratford, P. (1995). "Assessing disability and change on individual patients: a report of a patient specific measure." Physiotherapy Canada 47(4): 258-263.

Age Range

Adult: 18-64 years 

Administration Mode

Paper/Pencil 

Diagnosis

Knee Dysfunction; Multiple Sclerosis; Neck Injury; Pain 

Populations Tested

  • Joint Replacement
  • Knee Dysfunction
  • Low back pain
  • Lower Limb Amputees
  • Multiple Sclerosis
  • Neck Dysfunction and Whiplash 
  • Pubic Symphysis pain in pregnancy
  • Spinal Stenosis
  • Upper Extremity Musculoskeletal

Standard Error of Measurement (SEM)

Chronic Pain:

(Stratford et al, 1995; n = 63 with mechanical low back pain; mean age = 47 (12) years, Chronic Pain)

  • SEM = 0.41

Knee Dysfunction:

(Chatman et al, 1997; n = 38 patients with knee dysfunction; mean age = 47 (18) years, Knee Dysfunction)

  • SEM for individual activity analysis = 1.0
  • SEM for average of 5 activity items = 0.62

Lower Limb Amputees:

(Resnik and Borgia, 2011; n = 44 patients with unilateral lower limb amputation, current prosthesis users with limb loss at least 2 years prior to the study, mean age = 66 (13) years, Lower Limb Amputees)

Item
SEM
1
1.4
2
1.8
3
1.3
4
1.9
5
1.3
Total:
4.8

Neck Dysfunction:

(Westaway et al, 1998; n = 31 patients with neck pain; mean age = 40.4 (14.1) years, Neck Dysfunction)

  • SEM for a modified three activity version of the scale = 0.43

Spinal Stenosis:

(Cleland et al, 2012; n = 55 patients with lumbar stenosis; mean age = 69.2 (8); mean duration of low back pain = 13.1 (16.2) years, Spinal Stenosis)

  • SEM = 1.03

Minimal Detectable Change (MDC)

Chronic Pain: (Stratford et al 1995)

  • MDC = 2 points

Low Back Pain: (Maughan and Lewis, 2010)

  • MDC = 1.4 points

Lower Limb Amputees: (Resnik and Borgia, 2011)

Item
MDC90
1
3.3
2
4.2
3
3.1
4
4.5
5
3.1
Total:
11.2

Knee Dysfunction: (Chatman et al, 1997)

  • MDC = 1.5 points

Neck Dysfunction: (Westaway et al, 1998)

  • MDC = 2 points

Spinal Stenosis: (Cleland et al, 2012)

  • MDC = 2.4 points

 

Minimally Clinically Important Difference (MCID)

Spinal Stenosis:

(Cleland et al, 2012, Spinal Stenosis)

  • MCID = 1.34 points

UE Musculoskeletal:

(Hefford et al., 2012, UE Musculoskeletal)

  • MCID = 1.2 points

Cut-Off Scores

Not Established

Normative Data

Not Established

Test-retest Reliability

Chronic Pain:

(Stratford et al, 1995, Chronic Pain)

  • Excellent test-retest reliability (ICC = 0.97)

Knee Dysfunction:

(Chatman et al, 1997, Knee Dysfunction)

  • Excellent test-retest reliability (ICC = 0.84)

Neck Pain:

(Westaway et al, 1998, Neck Pain)

  • Excellent test-retest reliability on a modified three activity version of the scale (ICC = 0.92)

Spinal Stenosis:

(Cleland et al, 2012, Spinal Stenosis)

  • Adequate test-retest reliability (ICC = 0.59)

Interrater/Intrarater Reliability

Lower Back Pain:

(Maughan and Lewis, 2010, Lower Back Pain)

  • Excellent interrater reliability (ICC = 0.92)

Lower Limb Amputees:

(Resnik and Borgia, 2011, Lower Limb Amputees)

  • Excellent interrater reliability (ICC = 0.83)

UE Musculoskeletal:

(Hefford et al., 2012, UE Musculoskeletal)

  • Excellent interrater reliability (ICC2,1 = 0.713)

*Note a small positive change in the stable (as opposed to improved) group

Internal Consistency

Not Established

Criterion Validity (Predictive/Concurrent)

Chronic Pain:

(Stratford et al, 1995, Chronic Pain)

  • Excellent concurrent validity with Roland-Morris - average across 5 activities scores (r = -0.67)

Multiple Sclerosis:

(Hammer et al, 2005; n = 13; mean age = 47.9 years (8.4); 10 week Hippotherapy intervention; Swedish sample, Multiple Sclerosis)

  • Evidence of concurrent validity with the SF-36- Role Emotional (RE) Dimension

Neck Pain:

(Westaway et al, 1998, Neck Pain)

  • Excellent concurrent validity for a modified three activity version of the scale with:
    • Neck Dysfunction Index (r = 0.73 - 0.83)
    • Clinical prognosis rating (r = 0.64)

Construct Validity (Convergent/Discriminant)

A comparison of correlation coefficients determined good convergent validity of the Patient Specific Functional Scale (PSFS) with Global Rating of Change Scale (GRC), better than with the generic 36-item Short Form Health Survey (36-SF), possibly because both PSFS and GRC ask patients to self-identify areas of disability while a more generic measure would include items not relevant to the patient (Chatman et al, 1997).

Joint Replacement:

(Dill et al, 2012; n = 82 patients awaiting joint replacement; mean age = 70.3 (9.8), Joint Replacement)

  • Poor convergent validity with SF-36 Physical function scale (r = 0.22), SF-36 Physical Component Summary scale (r = 0.11)
  • Adequate convergent validity with the Western Ontario and McMasters University Arthritis Index (r = -0.37)
  • Poor discriminant validity with SF-36 Mental Health scale (r = 0.11)

Spinal Stenosis:

(Cleland et al, 2012, Spinal Stenosis)

  • Excellent convergent validity with the Global Rating of Change (r = 0.69)

Content Validity

Not Established

Face Validity

Not Established

Floor/Ceiling Effects

Floor effect observed in knee dysfunction patients: patients generally identify activities where substantial disability exists, and because score of “0” on activity means “unable to perform”  there is no space on the scale for the patient to demonstrate deteriorating abilities (Chatman et al, 1997)

No floor or ceiling effects observed for Lower Limb Amputees (Resnik and Borgia, 2011)

Responsiveness

Joint Replacement:

  • Moderate responsiveness (Standardized Response Mean (SRM) = 0.55; Guyatt’s Responsiveness Index(GRI) = 1.18)

Spinal Stenosis:

  • Large responsiveness (SRM = 0.91, GRI = 1.75)

Professional Association Recommendations

Recommendations from the Neurology Section of the American Physical Therapy Association’s StrokEDGE Taskforce, MSEDGE Taskforce, SCI EDGE Taskforce, and the TBI EDGE Taskforce are listed below. These recommendations were developed by a panel of research and clinical experts using a modified Delphi process.

 

For detailed information about how recommendations were made, please visit:  http://www.neuropt.org/go/healthcare-professionals/neurology-section-outcome-measures-recommendations

 

Abbreviations:

HR

Highly Recommend

R

Recommend

LS / UR

Reasonable to use, but limited study in target group  / Unable to Recommend

NR

Not Recommended

 

Recommendations based on level of care in which the assessment is taken:

 

Acute Care

Inpatient Rehabilitation

Skilled Nursing Facility

Outpatient

Rehabilitation

Home Health

MS EDGE

NR

UR

UR

UR

UR

 

Recommendations based on EDSS Classification:

 

EDSS 0.0 – 3.5

EDSS 4.0 – 5.5

EDSS 6.0 – 7.5

EDSS 8.0 – 9.5

MS EDGE

UR

UR

UR

UR

 

Recommendations for entry-level physical therapy education and use in research:

 

Students should learn to administer this tool? (Y/N)

Students should be exposed to tool? (Y/N)

Is this tool appropriate for use in intervention research studies? (Y/N)

MS EDGE

No

No

No

Considerations

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Bibliography

Chatman, A. B., Hyams, S. P., et al. (1997). "The Patient-Specific Functional Scale: measurement properties in patients with knee dysfunction." Physical Therapy 77(8): 820-829. Find it on PubMed

Cleland, J. A., Whitman, J. M., et al. (2012). "Psychometric properties of selected tests in patients with lumbar spinal stenosis." Spine J 12(10): 921-931. Find it on PubMed

Gill, S. D., de Morton, N. A., et al. (2012). "An investigation of the validity of six measures of physical function in people awaiting joint replacement surgery of the hip or knee." Clinical Rehabilitation 26(10): 945-951.

Hammer, A., Nilsagard, Y., et al. (2005). "Evaluation of therapeutic riding (Sweden)/hippotherapy (United States). A single-subject experimental design study replicated in eleven patients with multiple sclerosis." Physiother Theory Pract 21(1): 51-77. Find it on PubMed

Hefford, C., Abbott, J. H., et al. (2012). "The patient-specific functional scale: validity, reliability, and responsiveness in patients with upper extremity musculoskeletal problems." J Orthop Sports Phys Ther 42(2): 56-65. Find it on PubMed

Maughan, E. F. and Lewis, J. S. (2010). "Outcome measures in chronic low back pain." European Spine Journal 19(9): 1484-1494. Find it on PubMed

Resnik, L. and Borgia, M. (2011). "Reliability of outcome measures for people with lower-limb amputations: distinguishing true change from statistical error." Physical Therapy 91(4): 555-565. Find it on PubMed

Stratford, P. (1995). "Assessing disability and change on individual patients: a report of a patient specific measure." Physiotherapy Canada 47(4): 258-263.

Westaway, M. D., Stratford, P. W., et al. (1998). "The patient-specific functional scale: validation of its use in persons with neck dysfunction." Journal of Orthopaedic and Sports Physical Therapy 27(5): 331-338. Find it on PubMed

Year published

1995 

Instrument in PDF Format

Yes 
Approval Status Approved 
 
Attachments
Created at 10/30/2010 11:36 AM  by Dawood Ali 
Last modified at 12/4/2013 4:52 PM  by Jason Raad