title: Parkinson's disease sleep scale--validation of the revised version PDSS-2.
abstract: BACKGROUND
  The previous Parkinson's disease sleep scale (PDSS) is a 15-item visual analogue scale that assesses the profile of nocturnal disturbances in Parkinson's disease (PD) patients.
  
  
  OBJECTIVE
  To extend the scale so that it becomes a frequency measure scale with five categories and encompasses unmet needs such as restless legs syndrome, akinesia, pain, and sleep apnea.
  
  
  METHODS
  For validation of the PDSS-2, PD patients' ratings and investigators' interviews were compared to ratings from a semistructured interview with a caregiver/partner, and to related scales. PDSS-2 was repeated for test-retest-reliability after 1-3 days.
  
  
  RESULTS
  A total of 113 PD patients showed a mean (SD) total score of 16.5 (±8.9) (range: 2-40) indicating mild to moderate sleep disturbances. PDSS-2 item-total correlation for proving internal consistency was satisfactory (correlations >0.30). From a factor analysis, three subscales were derived: (1) "motor problems at night," (2) "PD symptoms at night" and (3) "disturbed sleep." The alpha coefficient for the total score was 0.73, for subscales 0.47 to 0.66. The test-retest-reliability intra-class-coefficient for the total score was 0.80, with 0.69 and 0.77 within the subscales. For discriminative validity, significant differences were found in the PDSS-2 total score depending on CGI and Hoehn and Yahr severity levels. A comparison between caregivers' and patients' ratings was carried out.
  
  
  CONCLUSIONS
  The PDSS-2, with an extended spectrum of nocturnal disabilities and easier use for patients, is a reliable, valid, precise, and potentially treatment-responsive tool for measuring sleep disorders in PD.
authors.affiliation: Paracelsus-Elena Hospital, Kassel, Germany. ctrenkwalder@gmx.de
authors.forename: Claudia
authors.initials: C
authors.lastname: Trenkwalder
authors.forename: Ralf
authors.initials: R
authors.lastname: Kohnen
authors.forename: Birgit
authors.initials: B
authors.lastname: Högl
authors.forename: Vinod
authors.initials: V
authors.lastname: Metta
authors.forename: Friederike
authors.initials: F
authors.lastname: Sixel-Döring
authors.forename: Birgit
authors.initials: B
authors.lastname: Frauscher
authors.forename: Julia
authors.initials: J
authors.lastname: Hülsmann
authors.forename: Pablo
authors.initials: P
authors.lastname: Martinez-Martin
authors.forename: Kallol Ray
authors.initials: KR
authors.lastname: Chaudhuri
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D012893:Sleep Wake Disorders / Q000175:diagnosis* / Q000209:etiology*; D013223:Statistics as Topic; D011795:Surveys and Questionnaires