Assessment of Psychometric Characteristics of Parkinson’s Disease Sleep Scale 2 and Analysis of a Cut-Off Score for Detecting Insomnia in Italian Patients with Parkinson’s Disease: A Validation Study

introduction: sleep disorders are frequent non-motor symptoms affecting patients with parkinson's disease (PD). Insomnia represents the most common sleep disorder. parkinson's disease Sleep Scale 2 (PDSS-2) is a specific tool to investigate sleep problems in PD. the general sleep disturbances scale (GSDS) was a general scale validated for the Italian population. our goal was to assess the psychometric characteristics of PDSS-2 and the GSDS in this population, calculating a cut-off score for insomnia symptoms by using subitems of PDSS-2. methods: patients admitted at the PD unit of the hospital of rome tor vergata outpatient clinic and those afferent to PD associations were asked to complete PDSS-2 and GSDS to be correlated to identify a cut-off for insomnia symptoms. Items 1,2,3,8,13 of PDSS-2 were used to detect insomnia. an ROC curve to assess a cut-off score for insomnia was determined. a cross-cultural analysis of PD population characteristics was performed. results: In total, 350 PD patients were recruited. cronbach's alpha was high for the total score (0.828 for PDSS-2 and 0.832 for GSDS). a cross-cultural analysis did not show any significant p-value. the ROC curve yielded an AUC of 0.79 (CI: 0.75-0.84). the cut-off value for insomnia disorder based on items 1,2,3,8,13 of PDSS-2 was >10, demonstrating a sensitivity of 76% and a specificity of 69% in determining the presence of subjective insomnia symptoms in PD. discussion: PDSS-2 is demonstrated to be a valid, specific tool to address sleep disturbances in PD patients. a cut-off score of 10 for items 1,2,3,8,13 was identified for detecting insomnia symptoms in PD patients.