title: How to identify tremor dominant and postural instability/gait difficulty groups with the movement disorder society unified Parkinson's disease rating scale: comparison with the unified Parkinson's disease rating scale.
abstract: BACKGROUND
  Formulas were developed to define tremor dominant (TD) and postural instability/gait difficulty (PIGD) phenotypes of Parkinson's Disease (PD) using the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS). TD and PIGD designations, based on the original Unified Parkinson's Disease Rating Scale (UPDRS), provided useful designations for classifying different phenotypes of PD. With the advent of the MDS-UPDRS, a valid set of calculations for these phenotypes is needed.
  
  
  METHODS
  UPDRS and MDS-UPDRS scores were collected on 877 PD patients. TD/PIGD scores were calculated using the UPDRS formula for all patients. Comparable TD and PIGD items from the MDS-UPDRS were used to calculate new ratios. Data were analyzed using receiver operating characteristic models.
  
  
  RESULTS
  The new MDS-UPDRS TD/PIGD ratios accounted for a significant area under the curve compared with the UPDRS classification. Optimal sensitivity and specificity were obtained with MDS-UPDRS cutoff scores of ≥1.15 for TD classification and ≤0.90 for PIGD.
  
  
  CONCLUSIONS
  The development of comparable and valid PIGD and TD scores from the MDS-UPDRS provides a clear method for clinicians and researchers to transition from the original UPDRS to the new MDS-UPDRS in categorizing patients with different clinical phenotypes. © 2013 Movement Disorder Society.
authors: Department of Neurological Sciences, Section of Movement Disorders, Rush University Medical Center, Chicago, IL 60612, USA. gstebbin@rush.edu
authors: Glenn T
authors: GT
authors: Stebbins
authors: Christopher G
authors: CG
authors: Goetz
authors: David J
authors: DJ
authors: Burn
authors: Joseph
authors: J
authors: Jankovic
authors: Tien K
authors: TK
authors: Khoo
authors: Barbara C
authors: BC
authors: Tilley
mesh_terms: D004185:Disability Evaluation; D005260:Female; D020233:Gait Disorders, Neurologic / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D008297:Male; D009460:Neurologic Examination; D010300:Parkinson Disease / Q000150:complications*; D004856:Postural Balance / Q000502:physiology*; D012372:ROC Curve; D012678:Sensation Disorders / Q000175:diagnosis* / Q000209:etiology*; D012720:Severity of Illness Index; D014202:Tremor