Validation of the Norwegian version of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale

Guido Alves; Yvonne Stavland Sørenes; Veslemøy Hamre Frantzen; Michaela Dreetz Gjerstad; Anders Ledaal Bjørnestad; Jodi Maple-Grødem; Elin Bjelland Forsaa; Ylva Hivand Hiorth; Karen Herlofson; Espen Benjaminsen; Kari Anne Bjørnarå; Espen Dietrichs; Roberta Balestrino; Carmen Gasca-Salas; Chi-Ying R Lin; Alvaro Sanchez-Ferro; Michelle H S Tosin; Tiago A Mestre; Monica M Kurtis; Pablo Martinez-Martin; Sheng Luo; Luowen Yu; Glenn T Stebbins; Christopher G Goetz; MDS COA Translation Steering Committee

doi:10.1016/j.prdoa.2025.100420

Validation of the Norwegian version of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale

Clin Park Relat Disord. 2026 Jan 6:14:100420. doi: 10.1016/j.prdoa.2025.100420. eCollection 2026.

Authors

Guido Alves^{1

2

3}, Yvonne Stavland Sørenes^{1

2}, Veslemøy Hamre Frantzen¹, Michaela Dreetz Gjerstad^{1

2}, Anders Ledaal Bjørnestad^{1

2}, Jodi Maple-Grødem^{1

3}, Elin Bjelland Forsaa^{1

2}, Ylva Hivand Hiorth^{1

4}, Karen Herlofson⁵, Espen Benjaminsen⁶, Kari Anne Bjørnarå⁷, Espen Dietrichs^{8

9}, Roberta Balestrino^{10

11

12}, Carmen Gasca-Salas^{13

14

15}, Chi-Ying R Lin¹⁶, Alvaro Sanchez-Ferro^{17

18}, Michelle H S Tosin¹⁹, Tiago A Mestre^{20

21}, Monica M Kurtis²², Pablo Martinez-Martin¹⁸, Sheng Luo²³, Luowen Yu²³, Glenn T Stebbins¹⁹, Christopher G Goetz¹⁹; MDS COA Translation Steering Committee

Affiliations

¹ Centre for Movement Disorders, Stavanger University Hospital, Stavanger, Norway.
² Department of Neurology, Stavanger University Hospital, Stavanger, Norway.
³ Department of Chemistry, Bioscience and Environmental Engineering, University of Stavanger, Stavanger, Norway.
⁴ Department of Physical Medicine and Rehabilitation, Stavanger University Hospital, Stavanger, Norway.
⁵ Department of Research, Sørlandet Hospital, Arendal, Norway.
⁶ Department of Neurology, Nordland Hospital Trust, Bodø, Norway.
⁷ Department of Neurology, Drammen Hospital, Vestre Viken Hospital Trust, Drammen, Norway.
⁸ Department of Neurology, Oslo University Hospital, Oslo, Norway.
⁹ Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
¹⁰ Vita-Salute San Raffaele University, Milan, Italy.
¹¹ Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy.
¹² Neurology and Neurorehabilitation Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy.
¹³ HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain.
¹⁴ Centro de Investigacion Biomedica en Red sobre Enfermedades Neurodegenerativas, Madrid, Spain.
¹⁵ School of Medicine, University CEU-San Pablo, Madrid, Spain.
¹⁶ Department of Neurology, Baylor College of Medicine, Houston, TX, USA.
¹⁷ Movement Disorders Unit, Neurology Department, Hospital Universitario 12 de Octubre, Madrid, Spain.
¹⁸ Centro de Investigacion Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Institute of Health Carlos III, Madrid, Spain.
¹⁹ Department of Neurological Sciences, Rush University Medical Center, Chicago, IL, USA.
²⁰ Parkinson's Disease and Movement Disorders Clinic, Division of Neurology, Department of Medicine, The Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
²¹ University of Ottawa Brain and Mind Institute, Ottawa, Ontario, Canada.
²² Movement Disorders Unit, Neurology Department, Hospital Ruber Internacional, Madrid, Spain.
²³ Department of Biostatistics & Bioinformatics, Duke University, Durham, NC, USA.

Abstract

Introduction: The Movement Disorder Society-revised version of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) is the gold standard assessment for evaluating Parkinson's disease (PD) symptoms and severity, but a validated Norwegian version is not yet available. We translated the original English MDS-UPDRS into Norwegian and tested the clinimetrics of the translated version following the MDS-established protocol for non-English language translations.

Methods: Two independent teams translated the English version of the MDS-UPDRS into Norwegian. After review of the back-translated English version, cognitive pretesting was performed in twelve PD patients at one study site. This was followed by large-scale testing completed by 351 native Norwegian-speaking PD patients at six centers across Norway. We applied confirmatory and exploratory factor analyses to determine the validity of the Norwegian version. Additional analyses were performed to test the reliability of the translated scale.

Results: Confirmatory factor analysis demonstrated that the factor structure of the Norwegian version was consistent with that of the English version, as indicated by comparative fit indexes of ≥0.90 for all four MDS-UPDRS parts. Exploratory factor analysis showed the same number of factors in each MDS-UPDRS part, compared to the English version, with some differences in item loadings. Cronbach's α values were >0.70 for all four MDS-UPDRS parts.

Conclusion: The Norwegian language MDS-UPDRS has good construct validity and internal consistency, meeting the requirements to be designated as the Official Norwegian Version of the MDS-UPDRS. We recommend using this validated version in both research and clinical practice.

Keywords: MDS-UPDRS; Parkinson’s disease; Reliability; Validation; Validity.