title: Gender-, age-, and race/ethnicity-based differential item functioning analysis of the movement disorder society-sponsored revision of the Unified Parkinson's disease rating scale.
abstract: Assess MDS-UPDRS items for gender-, age-, and race/ethnicity-based differential item functioning.
  
  
  
  Assessing differential item functioning is a core rating scale validation step. For the MDS-UPDRS, differential item functioning occurs if item-score probability among people with similar levels of parkinsonism differ according to selected covariates (gender, age, race/ethnicity). If the magnitude of differential item functioning is clinically relevant, item-score interpretation must consider influences by these covariates. Differential item functioning can be nonuniform (covariate variably influences an item-score across different levels of parkinsonism) or uniform (covariate influences an item-score consistently over all levels of parkinsonism).
  
  
  
  Using the MDS-UPDRS translation database of more than 5,000 PD patients from 14 languages, we tested gender-, age-, and race/ethnicity-based differential item functioning. To designate an item as having clinically relevant differential item functioning, we required statistical confirmation by 2 independent methods, along with a McFadden pseudo-R2magnitude statistic greater than "negligible."
  
  
  
  Most items showed no gender-, age- or race/ethnicity-based differential item functioning. When differential item functioning was identified, the magnitude statistic was always in the "negligible" range, and the scale-level impact was minimal.
  
  
  
  The absence of clinically relevant differential item functioning across all items and all parts of the MDS-UPDRS is strong evidence that the scale can be used confidently. As studies of Parkinson's disease increasingly involve multinational efforts and the MDS-UPDRS has several validated non-English translations, the findings support the scale's broad applicability in populations with varying gender, age, and race/ethnicity distributions. © 2016 International Parkinson and Movement Disorder Society.
authors.affiliation: Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Goetz
authors.affiliation: Department of Biostatistics, University of Texas Health Science Center, School of Public Health, Houston, Texas, USA.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Glenn T
authors.initials: GT
authors.lastname: Stebbins
authors.affiliation: Department of Biostatistics, University of Texas Health Science Center, School of Public Health, Houston, Texas, USA.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Biostatistics, University of Texas Health Science Center, School of Public Health, Houston, Texas, USA.
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Tilley
authors.affiliation: Columbia University Stroud Center at New York State Psychiatric Institute, New York, NY, USA.|Research Division, Hebrew Home at Riverdale, RiverSpring Health, New York, NY, USA.
authors.forename: Jeanne A
authors.initials: JA
authors.lastname: Teresi
authors.affiliation: Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, USA.
authors.forename: Douglas
authors.initials: D
authors.lastname: Merkitch
authors.affiliation: Department of Biostatistics, University of Texas Health Science Center, School of Public Health, Houston, Texas, USA.
authors.forename: Sheng
authors.identifier: 0000-0003-4214-5809
authors.initials: S
authors.lastname: Luo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis* / Q000453:epidemiology* / Q000208:ethnology; D011594:Psychometrics / Q000379:methods*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012955:Societies, Medical / Q000592:standards
keywords: MDS-UPDRS; Parkinson's disease; clinimetrics; differential item functioning; rating scales