Parkinson's Disease Sleep Scale-2: The Brazilian Version's Cross-Cultural Adaptation and Validation

<b>Objective</b> To translate, cross-culturally adapt, and validate the Brazilian version of the Parkinson's Disease Sleep Scale-2 (PDSS-2/BR). <b>Methods</b> This cross-sectional study addressed 80 patients with PD, and it was organized into two phases: 1) Translation and cross-cultural adaptation, which included 30 individuals in the scale's pretest stage and 2) Validation, when 50 individuals were assessed by the PDSS-2/BR, Pittsburgh Sleep Quality Index (PSQI), Parkinson's Disease Questionnaire-39 (PDQ-39), MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), and Hoehn and Yahr rating scale (HY); the PDSS-2/BR was retested 7 days later. The significance level was set at 5%. <b>Results</b> The participants rated the PDSS-2/BR as having more than 90% comprehension. It also showed good reliability (Cronbach's alpha = 0.782) and excellent test-retest reliability (ICC _interrater = 0.901; <i>p</i> = 0.570; ICC _intrarater = 0.905; <i>p</i> = 0.116). Additionally, the scale showed good precision, with low standard error of measurement (SEM _inter = 1.040; SEM _intra = 0.908), and moderate to strong correlation with the PSQI, MDS-UPDRS, and PDQ-39 scales (rho = 0.46-0.74); only the HY scale showed no correlation. <b>Discussion</b> The PDSS-2/BR is a reliable, precise, and valid instrument for evaluating sleep among Brazilian individuals with PD. Hence, it is expected to help researchers and clinicians improve the investigation of these symptoms, promoting early and assertive diagnoses and guiding the treatment and clinical management of this population.