Validation of the Albanian Neck Disability Index: A Reliable and Precise Tool for Assessing Disability in Young Adults with Chronic Cervical Pain

Background: Chronic neck pain is a prevalent musculoskeletal condition associated with functional limitations and reduced quality of life, representing a significant public health concern. The Neck Disability Index (NDI) is one of the most widely used patient-reported outcome measures for assessing neck-related disability. Although validated in multiple languages, a comprehensive psychometric evaluation of an Albanian version in a large clinical sample has been lacking. Methods: A methodological cross-sectional study was conducted to translate, culturally adapt, and evaluate the psychometric properties of the Albanian version of the NDI. The translation process followed standardized forward–backward cross-cultural adaptation procedures with authorization from the MAPI Research Trust. A total of 377 individuals with chronic cervical pain completed the questionnaire. Structural validity was assessed using Principal Component Analysis (PCA). Internal consistency was evaluated using Cronbach’s alpha, and test–retest reliability was assessed using intraclass correlation coefficients (ICC). Measurement error was estimated using the Standard Error of Measurement (SEM) and Minimal Detectable Change at the 95% confidence level (MDC95) at both item and total score levels. Results: Sampling adequacy was excellent (KMO = 0.948; Bartlett’s test p < 0.001). Structural validity supported a predominantly unidimensional structure, with a dominant component explaining 64.17% of the total variance. Internal consistency was excellent (Cronbach’s α = 0.99). Test–retest reliability was outstanding, with item-level ICC values ranging from 0.980 to 0.992 and a total score ICC of 0.989. Measurement error for the total score was low (SEM = 0.94; MDC95 = 2.60), indicating that changes greater than 2.60 points reflect real change beyond measurement error. Item-level MDC95 ranged from 0.36 to 0.67. Conclusions: The Albanian version of the NDI demonstrates strong structural validity, excellent internal consistency, high test–retest reliability, and low measurement error in individuals with chronic cervical pain. These findings are most applicable to relatively young, convenience-based Albanian-speaking populations, reflecting the characteristics of the study sample.