Translation and Psychometric Testing of the Norwegian Foot Functional Index Revised, Short Version.

Study Overview
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Brief Summary
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The aim of this study is to translate into Norwegian and cross-culturally adapt the Foot Functional Index- revised, short form (FFI-RS) according to international guidelines. Furthermore, the reliability and the validity, responsiveness as well as floor and ceiling effect of the Norwegian version of the FFI-RS will be determined.

Detailed Description
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Foot Functional Index, revised short form is a foot specific patient reported outcome measurement (PROM) which covers pain, stiffness, activity limitations, disability as well as psychosocial issues. The aim of this study is to translate into Norwegian and cross-culturally adapt Foot Functional Index revised, short form (NFFI-RS). Furthermore, the reliability, validity, interpretability and responsiveness will be determined. The Department of Physical Medicine and Rehabilitation at Oslo University Hospital has an ongoing double blind, randomized sham-controlled trial (RCT) comparing the effect of radial extracorporeal shock wave therapy (rESWT), sham rESWT, standardized exercise program and usual care for patients with longstanding plantar fasciopathy (NCT03472989). The testing of the psychometric properties of the NFFI-RS will include totally hundred patients, both from the mentioned RCT as well as patients with other foot diagnosis recruited from our department. The translation of the original FFI-RS into Norwegian has been done following the official guidelines. In the test-retest study fifty patients will complete the NFFI-RS at a one week interval. Smallest detectable change, measurement error, floor and ceiling effects as well as internal consistency will be calculated by using the baseline data. To decide the construct validity we will test the various hypothesis at baseline. To calculate the responsiveness and the minimal clinically important change three months data will be assessed. Patient Global Impression of Change Scale will be used to assess the minimal clinically important change and responsiveness of the NFFI-RS with ROC and AUC analyses.

Official Title
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Translation, Cross-culture Adaption of Foot Functional Index Revised, Short Version (FFI-RS) Into Norwegian. Testing of Psychometric Properties.

Conditions
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Foot Diseases, Plantar Fascitis

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Patients with pain localized in the foot Patients understanding oral and written Norwegian Exclusion Criteria: Patients without pain in the foot Patients not understanding oral and written Norwegian

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 100 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Foot Functional Index revised short version ( FFI-RS) | FFI-RS is a foot specific pain and function score. We will evaluate the reliability of the FFI-RS by testing the internal consistency (Cronbach's Alpha). Furthermore test-retest will be done with a second FFI-RS recording after one week (weighted Kappa). We will evaluate construct validity with other instruments (RAND-12 and NRS). To test the responsiveness of FFI-RS, we will evaluate the change in FFI-RS from baseline to 3 months with Patient Global Impression of Change score. | Baseline, 1 week, 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Numeric Rating Scale (NRS) | Change in heel pain (during Activity last week). NRS is a patient reported pain intensity scale ranging from 0 (no pain) to 10 (worst possible pain). NRS will by used for evaluating the construct validity of FFI-RS. | Baseline | 
| RAND-12 | Health related quality of life (12 items). RAND-12 will be used for evaluating the construct validity of FFI-RS. | Baseline | 
| Patient Global Impression Of Change Scale (PGIC) | 7-point scale ranging from very much improved to very much worse. PGIC will be used for evaluating the responsiveness of FFI-RS. | 3 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Foot Functional Index revised,, Translation and cultural adaption, Reliability, Validity, Responsiveness