Cross-cultural adaptation, reliability and validity of the Turkish version of the spine functional index.

Charles Philip Gabel,Antonio I Cuesta-Vargas,Sedef Karayazgan,Eda Tonga

doi:10.1186/s12955-015-0219-3

Abstract

BackgroundThe Spine Functional Index (SFI) is a patient reported outcome measure with sound clinimetric properties and clinical viability for the determination of whole-spine impairment. To date, no validated Turkish version is available. The purpose of this study is to cross-culturally adapted the SFI for Turkish-speaking patients (SFI-Tk) and determine the psychometric properties of reliability, validity and factor structure in a Turkish population with spine musculoskeletal disorders.MethodsThe SFI English version was culturally adapted and translated into Turkish using a double forward and backward method according to established guidelines. Patients (n = 285, cervical = l29, lumbar = 151, cervical and lumbar region = 5, 73% female, age 45 ± 1) with spine musculoskeletal disorders completed the SFI-Tk at baseline and after a seven day period for test-retest reliability. For criterion validity the Turkish version of the Functional Rating Index (FRI) was used plus the Neck Disability Index (NDI) for cervical patients and the Oswestry Disability Index (ODI) for back patients. Additional psychometric properties were determined for internal consistency (Chronbach’s α), criterion validity and factor structure.ResultsThere was a high degree of internal consistency (α = 0.85, item range 0.80-0.88) and test-retest reliability (r = 0.93, item range = 0.75-0.95). The factor analysis demonstrated a one-factor solution explaining 24.2% of total variance. Criterion validity with the ODI was high (r = 0.71, p < 0.001) while the FRI and NDI were fair (r = 0.52 and r = 0.58, respectively). The SFI-Tk showed no missing responses with the ‘half-mark’ option used in 11.75% of total responses by 77.9% of participants. Measurement error from SEM and MDC90 were respectively 2.96% and 7.12%.ConclusionsThe SFI-Tk demonstrated a one-factor solution and is a reliable and valid instrument. The SFI-Tk consists of simple and easily understood wording and may be used to assess spine region musculoskeletal disorders in Turkish speaking patients.

Highlights

The Spine Functional Index (SFI) is a patient reported outcome measure with sound clinimetric properties and clinical viability for the determination of whole-spine impairment
Spinal musculoskeletal problems are well-recognized with an associated functional limitation that may be considered as a major cause of disability
The SFI-Tk showed no missing responses, the ‘half-mark’ response was only used in 11.75% of responses, but this represented 77.9% of participants

Summary

Introduction

The Spine Functional Index (SFI) is a patient reported outcome measure with sound clinimetric properties and clinical viability for the determination of whole-spine impairment. Patient reported outcome (PRO) instruments are generally used for assessing the patients’ functional status, activity limitation, participation restriction, quality of life and pain level [1]. The Turkish version is available and used in clinical practice and research [17,18]. Another measurement option is the generic PRO such as the Short Form 36 Health Survey (SF-36) or its derivatives the SF-12 and SF-8, along with the EuroQol

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