Psychometric evaluation of the Albanian version of the Neck Disability Index in a large cohort of patients with cervical pain

Background The Neck Disability Index (NDI) is one of the most widely used instruments for evaluating neck pain disability. To date, no validated version has been available in Albanian. This study aimed to translate, culturally adapt, and evaluate the psychometric properties of the Albanian version of the NDI (ANDI). Methods The ANDI was developed using a standardized forward–backward translation method. A cross-sectional study was conducted among 566 participants with neck pain. Reliability was assessed through internal consistency (Cronbach’s alpha) and test–retest reliability (Intraclass Correlation Coefficient, ICC 2,1 ). Measurement error was estimated using the Standard Error of Measurement (SEM) and Minimal Detectable Change (MDC). Construct validity was examined with exploratory factor analysis (EFA) and item–total correlations (ITC). Results The ANDI showed excellent reliability, with Cronbach’s alpha values ranging from 0.981 to 0.993 and ICC 2,1 between 0.981 and 0.993. SEM values (0.104–0.178) and MDC values (0.288–0.493) confirmed strong measurement precision. ITC exceeded 0.96 for all items. EFA supported a unidimensional structure (KMO = 0.947, Bartlett’s test p < 0.001), consistent with the original instrument. Conclusion The ANDI is a reliable, valid, and culturally adapted measure of neck disability for Albanian-speaking populations, suitable for both clinical practice and research.