Enhancing the Cross-Cultural Adaptation and Validation Process of the Functional Rating Index in Spanish Patients with Low Back Pain: A Study Protocol

Abstract

Background: Patient-orientated evaluation methods are of paramount importance in assessing treatment outcomes. The Functional Rating Index (FRI) is one of the condition-specific questionnaires recommended for use with low back pain (LBP) patients. To date, no Spanish version has been published in the peer-reviewed literature. Objective: The aim of this study is to cross-culturally adapt and validate the FRI into Spanish in LBP population, according to established guidelines, and to evaluate its psychometric properties in different clinical settings. Design: Cross-cultural and validation study protocol. Setting: Five public and private physical therapy units in our area. Methods: Patients of any gender suffering nonspecific LBP will be recruited. Three phases will be conducted through a multi methodical approach, consisting of translation and cross-cultural adaptation of the FRI into Spanish: translation and cross-cultural adaptation of the FRI into Spanish, pilot testing to assess comprehensibility, and a validation phase considering aspects of reliability, construct validity, and structure of the instrument. Conclusion: The translation and cross-cultural adaptation of the FRI to Spanish language will be performed in a structured and evidence-based manner through a prospective, multicenter design. FRI usefulness in LBP patients in both public and private settings will be evaluated.