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Patient Specific Functional Scale

Patient Specific Functional Scale

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Purpose

The PSFS assesses functional ability to complete specific activities.

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Instrument Details

Acronym PSFS

Area of Assessment

Activities of Daily Living

Assessment Type

Patient Reported Outcomes

Administration Mode

Paper & Pencil

Cost

Free

Diagnosis/Conditions

  • Arthritis + Joint Conditions
  • Limb Loss & Impairment
  • Multiple Sclerosis
  • Pain Management

Key Descriptions

  • Patients rate their ability to complete an activity on an 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.

Time to Administer

Less than 4 minutes

Less than 4 minutes

Required Training

No Training

Age Ranges

Adults

18 - 64

years

Instrument Reviewers

Initially reviewed by Krista Van Der Laan PT, DPT, OCS in 2010; Updated with references for chronic pain, knee dysfunction, and amputee populations byLeah 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.

Updated in 2019 by 

Justyna Falat, B.S., OTS at University of Illinois at Chicago

Amy Reidy,  B.S., OTS at University of Illinois at Chicago

Artemis Sefandonakis,  B.S., OTS at University of Illinois at Chicago

Kylie Vance,  B.S., OTS at University of Illinois at Chicago

Body Part

Neck
Back
Lower Extremity

ICF Domain

Activity
Participation

Measurement Domain

Motor

Professional Association Recommendation

Recommendations for use of the instrument from the Neurology Section of the American Physical Therapy Association’s Multiple Sclerosis Taskforce (MSEDGE), Parkinson’s Taskforce (PD EDGE), Spinal Cord Injury Taskforce (PD EDGE), Stroke Taskforce (StrokEDGE), Traumatic Brain Injury Taskforce (TBI EDGE), and Vestibular Taskforce (Vestibular EDGE) 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)

Appropriate for use in intervention research studies? (Y/N)

Is additional research warranted for this tool (Y/N)

MS EDGE

No

No

No

Yes

Considerations

Do you see an error or have a suggestion for this instrument summary? Please e-mail us!

Chronic Pain

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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

Minimal Detectable Change (MDC)

Chronic Pain: (Stratford et al 1995)

  • MDC = 2 points

 

 

Test/Retest Reliability

Chronic Pain:

(Stratford et al, 1995, Chronic Pain)

  • Excellent test-retest reliability (ICC = 0.97)

 

Neck Pain:

(Westaway et al, 1998, Neck Pain)

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

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)

 

Neck Pain:

(Westaway et al, 1998, Neck Pain)

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

Back Pain

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Minimal Detectable Change (MDC)

Low Back Pain: (Maughan and Lewis, 2010)

  • MDC = 1.4 points

Interrater/Intrarater Reliability

Lower Back Pain:

(Maughan and Lewis, 2010, Lower Back Pain)

  • Excellent interrater reliability (ICC = 0.92)

Joint Pain and Fractures

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Standard Error of Measurement (SEM)

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

 

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

Hand Osteoarthritis (Wright et al., 2017; n= 35; Mean age= 63.8 (8.7))

  • SEM for entire group (n = 35): 0.56

 

Total knee arthroplasty (Berghmans et al., 2015; n=150; Mean age= 65 (8); “calculated from SD & ICC given in article”)

  • SEM for Complaint 1, 3 months post-surgery (n = 33): 1.82
  • SEM for Complaint 2, 3 months post-surgery (n= 33): 1.85
  • SEM for Complaint 3, 3 months post-surgery (n= 33): 1.38

Minimal Detectable Change (MDC)

Knee Dysfunction: (Chatman et al, 1997)

  • MDC = 1.5 points

 

Neck Dysfunction: (Westaway et al, 1998)

  • MDC = 2 points

Hand Osteoarthritis: (Wright et al., 2017; n= 35; Mean age= 63.8 (8.7))

  • MDC90 for entire group (n = 35): 1.30
  • MDC95 for entire group (n= 35): 1.56

Minimally Clinically Important Difference (MCID)

Hand Osteoarthritis: (Wright et al., 2017; n= 35; Mean age= 63.8 (8.7))

  • MCID for PSFS= 2.2-point change

Proximal humeral fracture (Backman et al., 2016; n= 53)

  • MCID= 2 or more points

Total knee arthroplasty (Berghmans et al., 2015; n=150; Mean age= 65 (8); “calculated from SEM (calculated from SDs & ICCs given in article))

  • MDC for Complaint 1, 3 months post-surgery (n=33): 5.04
  • MDC for Complaint 2, 3 months post-surgery (n=33): 5.13
  • MDC for Complaint 3, 3 months post-surgery (n=33): 3.83

Test/Retest Reliability

Knee Dysfunction:

(Chatman et al, 1997, Knee Dysfunction)

  • Excellent test-retest reliability (ICC = 0.84)

Hand Osteoarthritis (Wright et al., 2017)

  • Excellent test-retest reliability: (ICC = .81)

Total knee arthroplasty (Berghmans et al., 2015)

  • Adequate reliability: ICC= 0.73 complaint 1; ICC= 0.75 complaint 2; 0.86 complaint 3

Criterion Validity (Predictive/Concurrent)

Concurrent Validity:

Proximal humeral fracture (Backman et al., 2016)

  • Poor correlations between the PSFS with:
    • Patient Global Score (r = -0.03)
    • Grip Strength (r = 0.25)
    • Pain (r = -0.14)
  • Adequate correlations between the PSFS with:
    • Shoulder Function Assessment (r = -0.32)
    • WOOS (r = -0.32)
    • Physical Symptoms (r = -0.33)
    • Sports/Recreation/Work (r = -0.34)

Construct Validity

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 (= 0.22), SF-36 Physical Component Summary scale (= 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)

Convergent Validity:

Hand Osteoarthritis: (Wright et al., 2017; n= 35; Mean age= 63.8 (8.7))

  • Adequate correlation with PSFS scores to left hand grip strength and right hand grip strength posttreatment (r = 0.39, 0.36 respectively)
  • Adequate correlation with PSFS scores to DASH posttreatment (r = - 0.58)
  • Poor correlation with change in PSFS scores to changes in left and right hand grip strength scores and DASH (r = 0.06, 0.08, 0.13 respectively)

Total knee arthroplasty: (Berghmans et al., 2015)

  • Adequate correlation between the mean PSFS and total WOMAC score at 3 months (r = 0.41)
  • Adequate correlation between the mean PSFS score and GPE score at 3 months (r = -0.37)
  • Adequate correlation between the mean PSFS score and total WOMAC score at 1 year (r = 0.48)
  • Adequate correlation between the mean PSFS score and total GPE score at 1 year (r = -0.55)

Content Validity

Proximal humeral fracture (Backman et al., 2016; n= 53)

“Content validity was described based on the 47 activities stated in the PSFS, and thereafter coded according to the ICF coding rules into different components by the authors. 45 (96%) of the activities were coded into activity levels according to the ICF, and 29 (62%) of them could be found in the WOOS. From the results of this study, Backman et al. (2016) concluded that the PSFS has very good content validity as 96% of the stated activities could be classified in the ICF activity component and 62% were found in the WOOS.”

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)

Proximal humeral fracture

(Backman et al., 2016; n= 53; Mean age= 60; time post trauma or operation= 6 weeks (1))

  • Poor floor effect of 28% found for the PSFS in activity limitation at baseline
  • Poor ceiling effect of 48% found for the PSFS  in activity limitation at follow up.

Responsiveness

Joint Replacement:

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

Hand fractures and dislocations (Novak et al., 2014; n = 63; assessed from baseline (initial hand therapy assessment) to final (discharge from hand therapy)

  • Statistically significant improvement in overall PSFS scores from the initial (mean score of 3.2) to final (mean score of 8.1) assessment (p < 0.001)
  • Poor correlation between the

Proximal humeral fracture (Backman et al., 2016; n= 53)

The outcome in all variables was statistically significant and improved after shoulder rehabilitation, as was the PSFS (Table 4). There was total agreement (100%) between patients’ and physical therapists’ ratings of direction of outcome of rehabilitation in the GRC (better/worse/no change) and no systematic deviation could be detected between patients’ and physical therapists’ rating of level ( ± 0–7) of improvement (Sign test p - 0.34).

Sensitivity to Change 22 participants measured before (median 1) and after 2 months of shoulder rehabilitation (median 2).

Assessment

Median 1

Median 2

P value

PSFS total

2 (0-8)

9 (5-10)

<0.001

Patient global score (0-100)

45 (4-93)

16 (1-74)

<0.001

Shoulder function assessment (5-30)

19 (10-28)

7.5 (5-26)

<0.001

Grip strength (N)

215 (77-367)

254 (105-406)

<0.001

WOOS total (0-1900)

1043 (300-1529.5)

359.5 (60.5-1199)

<0.001

WOOS Physical symptoms (0-600)

276 (79-541)

102.75 (26-382)

<0.001

WOOS Sports/recreation/work (0-500)

260.5 (44-458)

114.5 (13.5-321)

<0.001

Pain (0-100)

50.25 (6.5-89.5)

13.5 (3-72)

0.001

Western Ontario Osteoarthritis of the shoulder Index (WOOS)

Total knee arthroplasty: (Berghmans et al., 2015)

Large change in effect size at 3 months and 1 year: between 1.71 and 2.89 respectively.

 

Responsiveness of the PSFS after 3 months

PSFS Domain

Effect Size

Standardized Response Mean

r With global perceived effect

r with Western Ontario and McMaster Universities Osteoarthritis Index (Function)

r with Western Ontario and McMaster Universities Osteoarthritis Index (Total)

Complaint 1 (0-10)

1.40

0.80

-0.33

0.31

0.31

Complaint 2 (0-10)

1.24

0.68

-0.28

0.34

0.33

Complaint 3 (0-10)

0.91

0.62

-0.20

0.29

0.28

Mean (0-10)

1.71

0.96

-0.37

0.42

0.41

 

Responsiveness of the PSFS after 12 months

PSFS Domain

Effect Size

Standardized Response Mean

r With global perceived effect

r with Western Ontario and McMaster Universities Osteoarthritis Index (Function)

r with Western Ontario and McMaster Universities Osteoarthritis Index (Total)

Complaint 1 (0-10)

2.20

1.12

-0.43

0.30

0.35

Complaint 2 (0-10)

2.11

1.16

-0.49

0.42

0.45

Complaint 3 (0-10)

1.70

1.05

-0.31

0.26

0.29

Mean (0-10)

2.89

1.48

-0.55

0.43

0.48

Multiple Sclerosis

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Criterion Validity (Predictive/Concurrent)

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

Limb Loss and Amputation

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Standard Error of Measurement (SEM)

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

Minimal Detectable Change (MDC)

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

Interrater/Intrarater Reliability

Lower Limb Amputees:

(Resnik and Borgia, 2011, Lower Limb Amputees)

  • Excellent interrater reliability (ICC = 0.83)

Musculoskeletal Conditions

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Standard Error of Measurement (SEM)

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)

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

Test/Retest Reliability

Spinal Stenosis:

(Cleland et al, 2012, Spinal Stenosis)

  • Adequate test-retest reliability (ICC = 0.59)

Interrater/Intrarater Reliability

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

Construct Validity

Spinal Stenosis:

(Cleland et al, 2012, Spinal Stenosis)

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

Responsiveness

Spinal Stenosis:

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

Older Adults and Geriatric Care

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Standard Error of Measurement (SEM)

Community-Dwelling Older Adults (Mathis, et. al, 2019; n=31; mean age= 81.1 years (8.3); mean body mass= 70.6 kg (15.0); mean height= 164.5 cm (9.8))

  • SEM for entire group (n=31): 1.0

Minimal Detectable Change (MDC)

Community-Dwelling Older Adults (Mathis, et. al, 2019)

  • MDC for entire group (n=31): 2.8

Test/Retest Reliability

Community-Dwelling Older Adults: (Mathis et al., 2019; n= 31; Mean age= 81.1 (8.3))

  • Excellent test-retest reliability: (ICC = .82)

Construct Validity

Convergent Validity:

Community-Dwelling Older Adults: (Mathis et al., 2019; n = 31);

  • Excellent correlation with the Activity-specific Balance Confidence Scale (r=0.68)
  • Excellent correlation with the Lower Extremity Functional Scale (r=0.81)
  • Adequate correlation with the Short Physical Performance Battery assessment (r=.37)
  • Poor correlation with the Berg Balance Scale (r=.17)
  • Poor correlation with Timed Up and Go assessment (r= - 0.26)

Bibliography

Berghmans, D. D., Lenssen, A. F., Rhijn, L. W. V., & Bie, R. A. D. (2015). The Patient-Specific Functional Scale: Its Reliability and Responsiveness in Patients Undergoing a Total Knee Arthroplasty. Journal of Orthopaedic & Sports Physical Therapy45(7), 550–556. doi: 10.2519/jospt.2015.5825

Bäckman, S. M., Stråt, S., Ahlström, S., & Brodin, N. (2016). Validity and sensitivity to change of the Patient Specific Functional Scale used during rehabilitation following proximal humeral fracture. Disability and Rehabilitation38(5), 487–492. doi: 10.3109/09638288.2015.1044623

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

Mathis, R., Taylor, J., Odom, B., & Lairamore, Chad. (2019). Reliability and validity of the patient-specific functional scale in community-dwelling older adults. Journal of Geriatric Physical Therapy, 42(3), E67-E72. DOI: 10.15.19/JPT.0000000000000188

Novak, C. B., Williams, M. M., & Conaty, K. (2014). Evaluation of the Patient-Specific Functional Scale in hand Fractures and Dislocations. Hand10(1), 85–87. doi: 10.1007/s11552-014-9658-2

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

Wright, H. H., Obrien, V., Valdes, K., Koczan, B., Macdermid, J., Moore, E., & Finley, M. A. (2017). Relationship of the Patient-Specific Functional Scale to commonly used clinical measures in hand osteoarthritis. Journal of Hand Therapy30(4), 538–545. doi: 10.1016/j.jht.2017.04.003

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