Psychometric properties of the Parkinson's Disease Sleep Scale – Brazilian version

Parkinson's Disease Sleep Scale (PDSS) is a specific scale for the assessment of sleep disturbances in subjects with Parkinson's Disease (PD). This cross-sectional study set out to validate the PDSS in a Brazilian Portuguese Version (PDSS-BR). Ninety-five patients with PD participated in the study; their PD symptoms were evaluated by Unified Parkinson's Disease Rating Scale (UPDRS sections I-IV) and Hoehn and Yahr scale. Patients completed Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), Beck Depression Inventory (BDI) and PDSS-BR. PDSS-BR internal consistency was satisfactory (Cronbach's alpha: 0.82; all PDSS-BR items were significantly and positively associated with total score). Test-retest reliability for total PDSS-BR score was 0.94. PDSS-BR score was highly correlated with sleep PSQI scale (r(s) = -0.63; p < 0.0001) and moderately with ESS (r(s) = -0.32; p < 0.001) and UPDRS sections I (r(s) = -0.38; p < 0.0001) and II (r(s) = -0.36; p < 0.0001) and BDI (r(s) = -0.55; p < 0.0001). Depressive symptoms, as determined by the BDI, were associated with significantly worse quality of nocturnal sleep, as measured by the PDSS-BR. The psychometric attributes of the PDSS-BR were satisfactory and consistent with those of previous studies. In summary, PDSS-BR can be useful for clinical and research purposes in Brazil.