SCOPA-sleep and PDSS: two scales for assessment of sleep disorder in Parkinson's disease.Mov Disord. 2008 Sep 15; 23(12):1681-8.MD
This study evaluated the comparative validity and usefulness of the Parkinson's Disease Sleep Scale (PDSS) and the Scales for Outcomes in PD-Sleep Scale (SCOPA-S), two disease-specific rating scales for assessing sleep disorders in Parkinson's disease (PD). Hoehn and Yahr staging (HY), SCOPA-Motor, Mini-Mental State Examination, Clinical Impression of Severity Index for PD, Hospital Anxiety and Depression Scale, EuroQoL, and SCOPA-Psychosocial, in addition to PDSS and SCOPA-S (night-time sleep (NS) and daytime sleepiness (DS) subscales), were applied to 187 consecutive PD patients. PDSS and SCOPA-S proved similar in acceptability, scaling assumptions, precision, and internal consistency (Cronbach's alpha = 0.82-0.84). Factor analysis revealed five separate factors for PDSS (67% of the variance) and one factor for each SCOPA-S subscale (60% of the variance for NS and 57% for DS). Correlation coefficient between PDSS and SCOPA-S NS was -0.60. Sleep scales correlated moderately with mood, low-to-moderate with HRQoL, and low with the rest of measures. PDSS and SCOPA-S DS discriminated between patients grouped by HY severity levels and disease duration. Cutoff points of 82/83 for PDSS and 6/7 for SCOPA-S NS were drawn to identify PD patients with sleep problems. Depression/anxiety scores explained 26% for PDSS and 22% for SCOPA-S NS scores. Both scales provide valid, reliable, and useful means to evaluate sleep disorders in PD. PDSS may be used to obtain a profile about potential causes of "bad sleep," but is barely useful to assess DS, whereas SCOPA-S assesses nocturnal sleep disorders and daytime somnolence at a similar extent, without exploring the potential causes.