Spanish translation and linguistic validation of the North Star Ambulatory Assessment for Duchenne muscular dystrophy functional evaluation.

Abstract

There is a need for reliable and properly validated outcome measures in Duchenne muscular dystrophy, both to monitor functional impairment and to assess the impact of new therapies. We aimed to perform a translation of the North Star Ambulatory Assessment scale into Spanish and a linguistic validation of the resulting Spanish version. A structured multistage process based on international guidelines was used, with the following steps: translation (preparation, forward translation, reconciliation, back translation, back translation review, clinicians' review), linguistic validation though pilot testing (cognitive interviewing, medical review, review of results and final changes), and finalization (proofreading, final report). No major difficulties were found during translation steps. Few changes were needed to reconcile forward translations. The linguistic validation process required several meetings to solve comprehension difficulties due to subtle nuances in the meaning of some words. The pilot study was carried out in 10 practitioners from different places in Spain, including both physiotherapists and specialists and registrars in physical medicine and rehabilitation. A total of 6 comments were obtained, including 2 comments on starting positions for items 4-5 (stand on one leg) and item 10 (stand on heels) and 2 comments on scoring instructions for item 3 (stand up from chair) and item 14 (jump). Our study has resulted in a convenient and reliable instrument for the quantification of functional abilities in boys with Duchenne muscular dystrophy in Spain. Our innovations in methods and our results could be used as a suggested template for the North Star Ambulatory Assessment linguistic validation in other languages.