Aim of the study was the cross-cultural adaptation and validation of the German version of the Scale for Outcomes in Parkinson's disease-Sleep Scale (SCOPA-Sleep) for assessment of night-time sleep problems (NS) and daytime sleepiness (DS). Eighty-three patients with Parkinson's disease completed the SCOPA-Sleep and a multitude of measures for assessment of validity (e.g., PSQI, ESS). Twenty patients completed the SCOPA-Sleep twice within 2 months for assessment of retest reliability. Sixty-four healthy controls were also included for validity estimation. Internal consistency (Cronbach's alpha) was good with coefficients of .801 and .854 for SCOPA-NS and SCOPA-DS, respectively. Test-retest reliability and inter-rater agreement were excellent. Factor analysis revealed two factors, one for each of the subscales NS and DS. Convergent validity was high with correlations of .797 between SCOPA-NS and PSQI, and .679 between SCOPA-DS and ESS. The German version of the SCOPA-Sleep showed good diagnostic accuracy. Optimal cutoff scores were calculated, resulting in an AUC of .908 for NS and of .959 for DS. The German version of the SCOPA-Sleep is a reliable and valid instrument for assessing NS and DS in patients with Parkinson's disease. As diagnostic accuracy is excellent, this scale can be recommended for routine assessment of both NS and DS in PD combined with other standard measures.
Keywords: Hypersomnia; Insomnia; Parkinson’s disease; Psychometrics; Reliability; SCOPA; Sleep; Sleepiness; Validity.