Establishing the Neck Disability Index as a Valid Tool for Assessing Persistent Neck Pain in the Albanian Population

Background and Objectives: The Neck Disability Index (NDI) is one of the most widely used instruments for assessing self-reported neck-related functional limitations. However, a validated Albanian version has not previously existed, limiting its application in Albanian-speaking populations. This study aimed to translate, culturally adapt, and evaluate the psychometric properties of the Albanian version of the NDI (ANDI), focusing on its reliability and internal consistency. Materials and Methods: A standard forward-backward translation methodology was used to develop the Albanian version of the NDI, followed by cultural adaptation. A total of 83 participants with neck pain completed the ANDI at two time points, three days apart. Test-retest reliability was assessed using the intraclass correlation coefficient (ICC), while internal consistency was evaluated using Cronbach's alpha and the item-total correlation (ITC). Results: The ICC values for all 10 sections of the ANDI ranged from 0.95 to 0.99, indicating excellent test-retest reliability. The highest reliability was observed in (personal care) and (pain intensity) with ICCs of 0.99 and 0.98, respectively. All sections demonstrated strong internal consistency, with ITC values ranging from 0.91 to 0.98 and a Cronbach's alpha of 0.96. Mean scores between test sessions showed negligible variation, further confirming score stability. Conclusions: The Albanian version of the NDI demonstrated excellent reliability and internal consistency, confirming its validity for use in clinical and research settings. This represents the first validated neck disability assessment tool for the Albanian-speaking population, supporting more inclusive musculoskeletal health assessment.