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Table 6 Clinimetric properties of patient-reported foot function measures

From: A review of the foot function index and the foot function index – revised

Instrument; author year

Reliability e.g., IRT, CTT ICC, kappa, test-retest

Cronbach’s alpha

Instrument /Domain N items/ Item generated sources

Validity (Face, content, criterion or construct) and other measures

Response to change

Completion time

Sample N diagnoses conclusion

FFI; Budiman Mak, E [7] 1991

CTT

Total: 0.96

FFI

Face: yes

Yes

10 minutes

N=87

ICC total: 0.87

Pain: 0.70

23 items

Criterion: r=0.52 FFI total scores vs 50 ft walked

Early rheumatoid arthritis

ICC (pain): 0.70

Disability: 0.93 Activity

Clinician and patient

Construct: Yes

Conclusion: Positive

ICC (disability): 0.84

Limitation 0.73

   

ICC (activity limitation): 0.81

    

FFI pain subscale (R/L foot); Saag, KG [23] 1996

CTT

0.94-0.96

FFI side-to-side; Clinician and patient

Face: Yes

  

N=63 Rheumatoid foot pain

ICC: 0.79-0.89

  

Content: Yes

  

Conclusion: Positive

FFI and AOS; Domsic, RT [24]1998

CTT

 

AOS

Criterion: AOS vs WOMAC disability

  

N=562

ICC: 0.97

 

18 items; Clinician

r=0.65 pain r=0.79

  

Dx: Ankle Osteoarthritis

Pain: 0.95

  

Construct: Yes

  

Conclusion: Positive

Disability: 0.94

      

FFI & FHSQ. Bennet, PJ [9]1998

CTT

0.85-0.88

FHSQ

Criterion: Yes

 

3-5 minutes

N=255 Dx: Hallux valgus osteoarthritis

ICC

Pain: 0.88

13 items

Construct: Yes, discriminant validity; Goodness of Fit

  

Conclusion: Positive

0.74-0.92

Function: 0.85

Clinician and Patient

    

pain 0.86

Footwear: 0.85

     

function 0.92

Foothealth: 0.87

     

footwear 0.74

      

foothealth 0.78

      

FFI (5 pt); Kuyvenhoven, MM [3] 2002

CTT

0.88-0.94

FFI (5 pt)

Concurrent validity: Yes

Yes

 

N=206

ICC 0.64-0.79

Total: 0.93

15 items

   

Dx: Non-traumatic foot complaint

Total: 0.76

Pain: 0.88

Clinician

   

Conclusion: Positive

Pain: 0.64

Disability: 0.92

     

Disability: 0.79

      

FFI & FIS; Helliwell,P [29] 2005

IRT

Not performed

FIS

Face: Yes

  

N=192

ICC

 

51 items

Content: Yes

  

Rheumatoid arthritis

Impairment/shoes: 0.84 Activities/participation: 0/96

 

2 subscales

Construct: Yes

  

Conclusion: Positive

  

clinician and patient

Goodness of Fit

   

FFI; Agel, J [25] 2005

ICC

 

FFI

   

N =54 FFI was tested in non-systemic or traumatic foot problems.

Total: 0.68

 

19 items items each from pain and difficulty subscales were deleted

   

FFI was good for individuals with low level functioning.

All subscale values were significant at .01 level

 

Clinician

   

Conclusion: Positive

FFI-R; Budiman-Mak, E [11] 2006

IRT

Total: 0.95

FFI-R

Criterion: Yes

 

15 minutes

N=92

Person reliability: 0.96

Pain: 0.93

Long form (68 items); Short form (34 items) Clinician and patient

Construct: Yes

  

Dx: Chronic foot and ankle problems

Item reliability:0.93

Disability: 0.93

 

Minimal floor effect (4.5%)

  

Conclusion: Positive

 

Activity limitation: 0.88

 

Goodness of Fit

   
 

Psychosocial: 0.86

     

FFI & SF 36: SooHoo, NF [27] 2006

Pearson Correlation of FFI to SF-36: Pain: -0.10 to −0.61;

 

FFI

Construct: Yes

  

N=69

Disability: -0.23 to −0.69

 

23 items

   

Forefoot and hindfoot complaints

Activity limitation: -0.23 to −0.61

 

3 domains

   

Moderate correlation between FFI and SF-36

      

Conclusion: Positive

FFI AOFAS; Baumhaur, JF [32] 2006

ICC AOFAS Summary Scores: Hallux 0.95 Lesser toes: 0.8 Pearson’s correlations mean value AOFAS Hallux vs. FFI: r=0.80, AOFAS lesser toes vs FFI: r=0.69; Pain subscale AOFAS Hallux vs. FFI summary score: r=0.31

 

FFI

Content: Yes

  

N=11

  

23 items

Criterion: Yes

  

Rheumatoid Hallux and lesser toes

  

3 domains

Ceiling effect noted in lesser toe activity subscale

  

Conclusion: Positive

FFI FHSQ ; Landorf, KB [101] 2007

ICC measures were reported; Minimal important difference (MID) was the focus of this clinical measure

 

MID

   

N=175

  

FHSQ Pain 14, Function 7, General health 9

   

Plantar fasciitis

  

FFI Pain 12, Function 7, Total 7

   

Conclusion: Positive

  

VAS

    

Pain 9

FFI, AOFAS; Ibrahim, T [33] 2007

Test-retest AOFAS; pre and post operation was no different; 41% response rate. Pearson correlation with FFI was −0.68 for all the subjective components of AOFAS. Hallux module subjective component was −0.46

 

AOFAS subjective component; Items dependent on modules

Criterion: yes

Yes

 

N=45 Foot and ankle problems

  

Clinician

Construct: Yes

  

AOFAS reliability and validity was tested.

   

Discriminant and predictive validity

  

Conclusion: positive with caution due to several limitations as mentioned in the paper.

FFI, FFI Taiwan Chinese; Wu, SH [36] 2008

ICC

CA

 

Criterion: Yes Floor effect 10%

  

N=79

Total 0.82

Total 0.94

    

Traumatic (fracture) non-traumatic plantar fasciitis foot problems

Pain 0.74

Pain 0.91

    

Conclusion: positive with caution, due to limitations (see article)

Disability 0.76 activity limitation 0.88

Disability 0.95

     
 

Activity limitation 0.75

Clinician and patients

    

Pearson’s correlations

 

FFI total with SF 36 r=−0.59 plan- tar fasciitis r=−0.61 ankle fracture

     

FFI, FFI- German Naal FD [34] 2008

ICC

CA total 0.97

FFI German 18 items pain and disability subscales 3 items were added to the instrument by patients

Construct yes Convergent validity FFI-G vs PCS of SF-36, VAS pain, disability UCLA activity scale

Yes

8.3 min

N= 53

Total 0.98

pain 0.90

Clinician and patients

   

Various foot problems required surgery

Pain 0.97

disability 0.95

Patient related difficulty 2.4 of rating scale 1-10

    

Disability 0.99

Cross cultural adaptation English to German with forward and backward protocol

    

Conclusion: positive

FFI-R; Rao S [75] 2009

This report is about minimal detectible change (MDC90) a measure of clinical importance.

 

FFI-R long 68 items

MDC Total 5 Pain 5

  

N=22 Orthoses treatment in mid foot pain

A result of orthoses intervention in midfoot arthritis

  

Activity limitation 7

  

Conclusion positive

   

Effect Size (ES) Total 0.4 Pain 0.6 Activity limitation 0.4

  

MDC and ES findings are significant

FFI-R; Rao, S [76] 2010

A measure of clinical importance of orthoses intervention

 

FFI-R long 68 items

MDC Total 5, Pain 5 Stiffness 6, Disanility 7, Activity limitation 7 Psychosocial 7 ES: Total 0.7, Pain 0.84, Stiffness 0.31, Disability 0.6, Limitation 0.57, Psycho social 0.32

  

N 30 Mid foot pain

       

Conclusion positive