Cultural adaptation, validity and reliability of the Turkish version of north star ambulatory assessment

Purpose The North Star Ambulatory Assessment (NSAA) is a functional motor outcome measure originally developed for patients with Duchenne muscular dystrophy (DMD). The aim of this study was to perform the cultural adaptation and investigate the validity and reliability of the Turkish version of the NSAA (T-NSAA) in DMD. Methods After translation process, internal consistency, interrater and test-retest reliability of the NSAA were determined by using the Cronbach Alpha Coefficient and Intraclass Correlation Coefficient (ICC), respectively. Absolute reliability was determined by using the Standard Error of Measurement (SEM) with minimal detectable change at 95% limits of confidence (MDC95). Lower limb functionality of children was evaluated by Vignos Lower Extremity Scale (VLERS). To establish convergent validity, the correlations between T-NSAA and Motor Function Measure (MFM-32), 6-minute walk test (6-MWT), and VLERS were analyzed by using the Spearman's correlation coefficient. Results The study was completed with 86 patients with DMD whose age were mean 104.56 +/- 24.66 months. The internal consistency (Cronbach's alpha = 0.94), intra-reliability (ICC = 0.977) and inter-reliability (ICC = 0.972) of T-NSAA were excellent. SEM and MDC values were low indicating satisfactory absolute agreement (< %10). The T-NSAA had strong correlations with the MFM-total score, 6-MWT, and VLERS (p < 0.01). Conclusion T-NSAA is a valid and reliable tool to assess ambulatory status of Turkish-speaking DMD population.