Turkish Adaptation Study of the Generic Functional Index

Turkish Adaptation, Validity and Reliability Study of the Generic Functional Index

The Generic Functional Index is a scale developed to assess the general functional status of individuals. This study aims to evaluate the validity and reliability of the Turkish version of the Generic Functional Index. The adaptation process was designed to follow a standardized translation protocol, including forward translation, expert committee review, back-translation, pilot testing, and psychometric analyses. Data will be collected from individuals with musculoskeletal problems. Psychometric testing will include test-retest reliability, internal consistency, and construct validity analyses.

The main hypotheses of this study are as follows:

1. The Turkish version of the Generic Functional Index will demonstrate high test-retest reliability when administered to individuals with musculoskeletal disorders.
2. The scores of the Turkish version of the Generic Functional Index will show a significant positive correlation with the scores of the Functional Independence Measure in individuals with musculoskeletal disorders.

Study Overview

• Status: Completed
• Conditions: Musculoskeletal Diseases
• Intervention / Treatment: Other: Internal consistency and Reliability; Other: Translating the Generic Functional Index into Turkish and Related Processes; Other: Validity

Detailed Description

Functional assessment is a fundamental component in evaluating the impact of health conditions on individuals' daily lives and in guiding rehabilitation strategies. The Generic Functional Index is a multidimensional instrument developed to assess overall functional status by capturing the effects of a person's problem on their daily activities, mobility, pain, and self-care performance. There is currently no validated Turkish version of the Generic Functional Index available for use in musculoskeletal populations.

This study aims to translate and culturally adapt the Generic Functional Index into Turkish and to investigate its psychometric properties in individuals with musculoskeletal disorders. The adaptation will follow an internationally recognized translation methodology, including forward translation, synthesis, back-translation, expert committee review, and pre-testing. Psychometric evaluation will involve data collection from individuals with musculoskeletal conditions, with analyses focusing on internal consistency, test-retest reliability, and construct validity.

Construct validity will be examined by analyzing the relationship between the Turkish Generic Functional Index and the Functional Independence Measure, which is a widely used tool for assessing independence in daily living activities. A strong correlation between these tools will support the convergent validity of the Turkish Generic Functional Index.

This study is significant because a valid and reliable Turkish version of the Generic Functional Index will provide clinicians and researchers with a standardized tool for evaluating functional limitations in Turkish-speaking populations with musculoskeletal disorders. It will also contribute to the international applicability of the Generic Functional Indexby expanding its use to different cultural and linguistic contexts.

• Study Type: Observational
• Enrollment (Actual): 200

Contacts and Locations

Study Locations

• Turkey (Türkiye)
  • Beyoglu
    • Istanbul, Beyoglu, Turkey (Türkiye), 34065
      • Istanbul Bilgi University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Probability Sample

Study Population

Participants with musculoskeletal conditions

Description

Inclusion Criteria:

• Being 18 years of age or older,
• Turkish literacy,
• Cognitive competence,
• Having a musculoskeletal disorder

Exclusion Criteria:

• Those with acute functional impairment
• Those with cognitive impairment, or
• Those with a mental or physical condition that would prevent them from understanding the scale.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Participants with musculoskeletal conditions; The sample will include adult individuals presenting with various musculoskeletal disorders, including but not limited to low back pain, osteoarthritis, tendinopathies, or other soft tissue conditions, which may influence their functional status.

Other: Internal consistency and Reliability; The internal consistency of the items will be tested with Cronbach alpha. Test-retest reliability will be tested with intraclass correlation coefficient.; Other: Translating the Generic Functional Index into Turkish and Related Processes; The translation process will follow a specific protocol in accordance with the guidelines. It will include two independent forward translations and one back-translation, conducted after obtaining written permission from the original authors. Discrepancies between translations will be reviewed by an expert committee to resolve terminological and cultural differences. The process will ensure conceptual and cultural equivalence between the original English version and the Turkish version. The final version of the questionnaire will be adapted to the target population and finalized in consultation with the original authors.; Other: Validity; Content validity will be calculated with the Content Validity Index, which is a result of expert opinions in terms of clarity, difficulty, and suitability of the Turkish version of the Generic Functional Index.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The Turkish Version of Generic Functional Index	This index is designed for use across a wide range of musculoskeletal and functional conditions and comprises four parts: Part 1 - Global Status: Patients rate their overall post-injury status on a 0-10 scale, multiplied by 10 to yield a percentage (range: 0-100). Part 2 - Duties and Pain: Assesses functional duties and pain level, each on a 0-10 scale converted to percentages (range: 0-100 each). Part 3 - Functional Limitations: A 10-item checklist (mobility, dressing, sleep, etc.), with full or half points; total score (0-10) is multiplied by 10 for a 100-point scale. Part 4 - Patient-Specific Index: Patients rate up to 5 activities on a 0-10 scale (0 = worst, 10 = best); total is doubled to yield a percentage (range: 0-100). Lower scores indicate greater disability; higher scores reflect better function.	T0 and T1 (Baseline and after 1 week after)
Functional Independence Measure	Functional Independence Measure will be used to examine the construct validity of the Turkish version of the Generic Functional Index. The Functional Independence Measure is a widely accepted and validated tool that assesses functional independence in daily activities through 18 items across motor and cognitive domains, scored on a 7-point scale. Since both instruments aim to evaluate functional status, a significant correlation between Functional Independence Measure and Generic Functional Index scores would support the convergent validity of the Generic Functional Index. Functional Independence Measure's established use in rehabilitation and its robust psychometric properties make it an appropriate reference measure for this validation study. Total Functional Independence Measure scores range from 18 to 126, where lower scores indicate complete dependence and higher scores reflect complete functional independence.	Baseline

Collaborators and Investigators

• Sponsor: Istanbul Bilgi University
• Investigators: Study Director: Elif Elcin Dereli, Prof., Istanbul Bilgi University; Principal Investigator: Selina Kara, BSc., Istanbul Bilgi University

Study record dates

Study Major Dates

• Study Start (Actual): July 1, 2025
• Primary Completion (Actual): May 1, 2026
• Study Completion (Actual): June 1, 2026

Study Registration Dates

• First Submitted: May 27, 2025
• First Submitted That Met QC Criteria: May 27, 2025
• First Posted (Actual): June 4, 2025

Study Record Updates

• Last Update Posted (Actual): June 26, 2026
• Last Update Submitted That Met QC Criteria: June 25, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: function; validity; reliability; musculoskeletal; Generic Functional Index
• Additional Relevant MeSH Terms: Musculoskeletal Diseases; Health Care Quality, Access, and Evaluation; Investigative Techniques; Epidemiologic Research Design; Epidemiologic Methods; Health Care Evaluation Mechanisms; Quality of Health Care; Public Health; Environment and Public Health; Evaluation Studies as Topic; Reproducibility of Results
• Other Study ID Numbers: IstanbulBUFC9

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No