title: The internal consistency and validity of the Self-Assessment Parkinson's Disease Disability Scale.
abstract: OBJECTIVE
  To test the consistency and validity of the Self-assessment Parkinson's Disease Disability Scale in patients with Parkinson's disease living at home.
  
  
  METHODS
  Patients with Parkinson's disease responded to a set of questionnaires. In addition, an observation of the performance of daily activities was carried out on a subgroup.
  
  
  METHODS
  Patients with Parkinson's disease living at home (n = 142).
  
  
  METHODS
  The Self-assessment Parkinson's Disease Disability Scale (SPDDS), the Hoehn & Yahr Rating Scale (H&Y), and the Sickness Impact Profile (SIP68). The observation concerned nine activities that correspond to items of the SPDDS questionnaire.
  
  
  RESULTS
  Internal consistency of the SPDDS was very high (Cronbach's alpha = 0.97; reliability rho = 0.97). The items of the SPDDS are hierarchical (Loevinger's H = 0.64): patients had least difficulty with 'washing' and 'brushing teeth' and most difficulty with 'turning in bed', 'travelling by public transport' and 'writing a letter'. Validity of the SPDDS was good: the relationship between the SPDDS questionnaire and the H&Y rating scale, the SIP68 and the results of the observation was strong and significant.
  
  
  CONCLUSIONS
  The SPDDS is a unidimensional instrument measuring disabilities in Parkinson's disease patients living at home.
authors.affiliation: Practice for Physical Therapy and Manual Therapy de Traay Driebergen, The Netherlands.
authors.forename: M A
authors.initials: MA
authors.lastname: Biemans
authors.forename: J
authors.initials: J
authors.lastname: Dekker
authors.forename: L H
authors.initials: LH
authors.lastname: van der Woude
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006233:Persons with Disabilities / Q000145:classification*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000145:classification* / Q000503:physiopathology / Q000523:psychology; D012111:Residence Characteristics; D012647:Self-Assessment; D012720:Severity of Illness Index; D018434:Sickness Impact Profile; D018709:Statistics, Nonparametric; D011795:Surveys and Questionnaires / Q000592:standards*