Validation of the Portuguese MDS‐UPDRS: Challenges to Obtain a Scale Applicable to Different Linguistic Cultures

Background The MDS‐UPDRS has been available in English since 2008, showing satisfactory clinimetric results and being proposed as the new official benchmark scale for Parkinson's disease (PD), being cited as a core instrument for PD in the National Institutes of Neurological Disorders and Stroke Common Data Elements program. For this reason, the MDS created guidelines for development of MDS‐UPDRS official, clinimetrically validated translations. Objective This study presents the formal process used to obtain the officially approved Portuguese version of the MDS‐UPDRS. Methods The study consisted of three phases: (1) Independent translation by Portuguese and Brazilian teams followed by a challenging consensus process that this article particularly emphasizes; (2) Cognitive pretest involving raters and patients from both Portugal and Brazil; (3) Validation test with a sample of 367 native Portuguese‐speaking PD patients. Results The overall factor structure of the Portuguese version was consistent with the English version based on a comparative fit index ≥0.96 for all four parts of the MDS‐UPDRS. Conclusion This version can be designated as the official Portuguese version of the MDS‐UPDRS.