Psychometric properties of the italian version of the Total Disability Index in patients with spine pain and disability. An italian cross-cultural adaptation, validation and translation

SUMMARY Background. Low back pain and neck pain are musculoskeletal disorders with the highest prevalence in the adult population. Spinal practices usually use formal questionnaires to asses and quantify pain and disability in people that suffer from back and neck pain, the aim of this study was to describe the translation and cross-cultural adaptation process of the English Total Disability Index (TDI) ‒ which is a more universal disability assessment ‒ into Italian version. Methods. The English version of the TDI has been translated according to international guidelines. The measurement properties (construct validity and reliability) have been tested according to COSMIN checklists. Exploratory Factor Analysis (EFA) was used to analyze structural validity. Cronbach’s α was calculated to assess the internal consistency and the Intraclass Correlation Coefficient (ICC) was calculated to estimate the reliability. The Functional Rating Index (FRI), the EuroQol Health Questionnaire 5 Dimensions (EQ-5D) and a Visual Analogue Scale (VAS) were used to assess the validity of the construct. Results. All the items were similar in meaning to the originals. EFA showed a mono-factorial structure. Cronbach’s α was 0.857 and the ICC was 0.821. The Pearson’s Correlation Coefficient showed significant correlations (p < 0.01) between SFI and FRI, EQ-5D and VAS items. Conclusions. Based on the results obtained, we suggest the use of TDI in daily clinical practice, also promoting its continuation in the field of scientific research.