title: Parkinson's disease severity levels and MDS-Unified Parkinson's Disease Rating Scale.
abstract: BACKGROUND
  Severity of PD is usually assessed by means of the motor and disability-based Hoehn and Yahr staging (HY), or clinician and patient global perceptions. Scores of more detailed assessments, as the MDS-UPDRS, have not been translated to a grading that allows assignment of score sections to severity levels. The objective of the present study is to determine cut-off points for PD severity levels based on the MDS-UPDRS.
  
  
  METHODS
  International, observational study. Applied assessments were: HY, MDS-UPDRS, Clinical Impression for Severity Index, and Clinical and Patient Global Impression of Severity. The coincidence in severity level (mild, moderate, severe) of at least two clinical classifications plus the patient's gradation was considered "the criterion of severity". Cut-off values for each MDS-UPDRS subscale was determined by triangulation of: 1) percentile 90 of the subscale total score; 2) receiver operating characteristic (ROC) analysis; and 3) ordinal logistic regression (OLR) model.
  
  
  RESULTS
  Sample was composed of 452 consecutive PD patients without dementia, 55.3% males, age 65.1 ± 10.7 years and PD duration 8.7 ± 6.3 years. All HY stages were represented. The "criterion", classified 275 patients (60.8% of the sample) as: mild PD, 149 (54.2%); moderate, 82 (29.8%); and severe, 44 (16%). The following MDS-UPDRS cut-off points between mild/moderate and moderate/severe levels were found: Part 1: 10/11 and 21/22; Part 2: 12/13 and 29/30; Part 3: 32/33 and 58/59; and Part 4: 4/5 and 12/13.
  
  
  CONCLUSIONS
  Cut-off points to classify PD patients as mild, moderate, or severe on the basis of their MDS-UPDRS scores are proposed.
authors.affiliation: National Center of Epidemiology and CIBERNED, Carlos III Institute of Health, Madrid, Spain. Electronic address: pmartinez@isciii.es.
authors.forename: Pablo
authors.initials: P
authors.lastname: Martínez-Martín
authors.affiliation: National Center of Epidemiology and CIBERNED, Carlos III Institute of Health, Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Rodríguez-Blázquez
authors.affiliation: Department of Movement Disorders and Neurodegeneration, CIREN, La Habana, Cuba.
authors.lastname: Mario Alvarez
authors.affiliation: Department of Neurology, Hospital Ramos Mejia, Buenos Aires, Centro Universitario de Neurología de la Universidad de Buenos Aires (UBA), Argentina.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Arakaki
authors.affiliation: Movement Disorders Unit, Department of Neuroscience, Hospital Xanit International, Benalmádena, Málaga, Spain.
authors.forename: Víctor Campos
authors.initials: VC
authors.lastname: Arillo
authors.affiliation: CETRAM, Facultad de Ciencias Médicas Universidad de Santiago de Chile, Chile.
authors.forename: Pedro
authors.initials: P
authors.lastname: Chaná
authors.affiliation: Movement Disorders Unit, Department of Neurology, Universidad Nacional de Colombia, Bogotá, Colombia.
authors.forename: William
authors.initials: W
authors.lastname: Fernández
authors.affiliation: Department of Neurology, Hospital Ramos Mejia, Buenos Aires, Centro Universitario de Neurología de la Universidad de Buenos Aires (UBA), Argentina.
authors.forename: Nélida
authors.initials: N
authors.lastname: Garretto
authors.affiliation: Movement Disorders Unit, Department of Neurology, Hospital Ramon y Cajal, IRYCIS, Madrid, Spain.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Martínez-Castrillo
authors.affiliation: Movement Disorders Unit, Instituto Nacional de Neurologia y Neurocirugia, Mexico, DF, Mexico.
authors.forename: Mayela
authors.initials: M
authors.lastname: Rodríguez-Violante
authors.affiliation: Movement Disorder and Biostatistics Units, Neurological Service, Carlos Andrade Marín Hospital and Medicine Faculty, Pontifical Catholic University of Ecuador, Quito, Ecuador.
authors.forename: Marcos
authors.initials: M
authors.lastname: Serrano-Dueñas
authors.affiliation: Movement Disorders Section, Raul Carrea Institute for Neurological Research (FLENI), Buenos Aires, Argentina.
authors.forename: Diego
authors.initials: D
authors.lastname: Ballesteros
authors.affiliation: Department of Statistics, Centre of Human and Social Sciences, Spanish Council for Scientific Research, Madrid, Spain.
authors.forename: Jose Manuel
authors.initials: JM
authors.lastname: Rojo-Abuin
authors.affiliation: National Parkinson Foundation International Centre of Excellence, King's College Hospital, King's College, London.
authors.forename: Kallol Ray
authors.initials: KR
authors.lastname: Chaudhuri
authors.affiliation: Movement Disorders Section, Raul Carrea Institute for Neurological Research (FLENI), Buenos Aires, Argentina.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Merello
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007391:International Cooperation; D008297:Male; D008875:Middle Aged; D019370:Observation; D010300:Parkinson Disease / Q000175:diagnosis* / Q000503:physiopathology*; D012720:Severity of Illness Index; D055815:Young Adult
keywords: Assessment; MDS-UPDRS; Parkinson's disease; Severity; Staging