Validation of the Parkinson's disease sleep scale in Japanese patients: a comparison study using the Pittsburgh Sleep Quality Index, the Epworth Sleepiness Scale and Polysomnography.

OBJECTIVE: Characteristic sleep disturbance in patients with Parkinson's disease (PD) was evaluated using a subjective questionnaire called the PD sleep scale (PDSS). In this study we sought to examine the relationship between the results from the PDSS with those from the Pittsburgh Sleep Quality Index (PSQI), the Epworth Sleepiness Scale (ESS), and polysomnography (PSG) in Japanese PD patients.

SUBJECTS AND METHODS: Subjects were 79 PD patients and 79 age and gender matched controls. The length of morbidity in patients with PD was 8.4+/-8.0 years, and their Hoehn and Yahr grade was 2.9+/-1.0. All subjects completed the PDSS, PSQI, and ESS questionnaires, and we compared the results from patients with PD to controls. We also evaluated the correlation among the PDSS, PSQI, and ESS in patients with PD. Moreover, we performed PSG on 33 of 79 PD patients, and examined the correlation between the PDSS and PSG.

RESULTS: PDSS total scores and subscales from patients with PD were significantly lower than those in controls, except for items 3, 8, and 14. PDSS scores had significant internal consistency and significant correlation with PSQI and ESS scores. The total PDSS score also correlated with sleep efficiency as measured by PSG. In subscales of the PDSS, night psychosis was negatively correlated with percentage of REM sleep without atonia on PSG.

DISCUSSION: Based on our comparisons with PSQI, ESS, and PSG, the PDSS appears to be a reliable tool to evaluate the characteristics of sleep disturbances in PD patients.