Clinically relevant cut-off values for the Parkinson's Disease Sleep Scale-2 (PDSS-2): a validation study.
Sleep disturbances are a major problem encountered by neurologists attending Parkinson's disease (PD) patients. The Parkinson's Disease Sleep Scale-2 (PDSS-2) assesses a wide spectrum of disease-specific sleep problems and is easy to administer as a patient self-rating scale. The validation study showed that the scale is reliable, valid, and precise. Until now, however, only one Japanese study has assessed cut-off scores to define poor sleepers.



In this context we aimed to determine the PDSS-2 cut-off values that define a sleep disturbance severe enough to require referral of the patient to a sleep center or the need for specific treatment.



Inpatients with idiopathic PD consecutively admitted to our hospital were enrolled. Patients completed the PDSS-2. The attending physician, who was blinded to the PDSS-2 results, but familiar with the patients' history and current disease status, completed a questionnaire consisting of two general questions on the presence of PD-specific and non-PD related sleep problems. Statistical analysis was performed to determine cut-off values for the PDSS-2 and correlation with the physician's evaluation of sleep disturbance severity. A natural cohort of non-PD patients with sleep disorders represented the control group.



The sample consisted of 52 (56%) men and 41 (44%) women with an average age of 69.22 ± 8.74 years. PDSS-2 showed a sensitivity of 77.6% and a specificity of 74.3% in relation to physician's evaluation of PD-specific sleep problems. According to the physician's evaluation, PD-specific sleep disturbances occurred in 62% of the patients. 83% of patients with PDSS-2 scores ≥18 had clinically relevant sleep disturbances compared to only 33% of PD patients with scores <18. The severity of PD-specific sleep problems was well correlated with the PDSS-2 total score (r = 0.49).



To our knowledge, this is the first study to define PDSS-2 cut-off values for the severity of sleep disturbances in a European PD sample. Our study shows that scores ≥18 define clinically relevant PD-specific sleep disturbances.
Paracelsus Elena Hospital, Kassel, Germany; Department of Clinical Neurophysiology, University of Göttingen, Göttingen, Germany. Electronic address: luciamuntean@yahoo.com.
Maria-Lucia
ML
Muntean
Somni Bene Institute for Clinical Research and Sleep Medicine Schwerin and Medical Center University of Rostock, Rostock, Germany.
Heike
H
Benes
Paracelsus Elena Hospital, Kassel, Germany; Department of Neurology, Philipps-University, Marburg, Germany.
Friederike
F
Sixel-Döring
National Parkinson Foundation Centre of Excellence, Kings College Hospital, London, United Kingdom.
Kallol Ray
KR
Chaudhuri
Department of Neurology, Dokkyo Medical University, Tochigi, Japan.
Keisuke
K
Suzuki
Department of Neurology, Dokkyo Medical University, Tochigi, Japan.
Koichi
K
Hirata
Psychologische Hochschule, Berlin, Germany.
Johannes
J
Zimmermann
Paracelsus Elena Hospital, Kassel, Germany; Department Neurosurgery, University of Göttingen, Göttingen, Germany.
Claudia
C
Trenkwalder
D000368:Aged; D005260:Female; D006801:Humans; D008297:Male; D010300:Parkinson Disease / Q000150:complications*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D012893:Sleep Wake Disorders / Q000175:diagnosis*; D011795:Surveys and Questionnaires
PDSS-2; Parkinson's disease; Sleep assessment