Diagnostic value of the REM sleep behavior disorder screening questionnaire in Parkinson's disease

Objective: We aimed to validate the rapid eye movement (REM) sleep behavior disorder (RBD) screening questionnaire (RBDSQ) in 2 independent samples of patients with Parkinson's disease (PD) using different settings when performing the investigations. Methods: The RBDSQ was administered to two independent samples of 52 and 75 consecutive PD patients investigated with video-polysomnography (vPSG). Results: In sample A, the RBDSQ identified 46/52 (88.5%) patients correctly. In sample B, 50/75 (66.7%) patients were identified correctly. Considering a cut-off score of >= 5 as a positive test result, sample A showed a sensitivity of 0.90 and a specificity of 0.87, sample B showed a sensitivity of 0.68 and a specificity of 0.63. Main differences between both groups were that patients of sample A underwent a sleep history including RBD assessment prior to administration of the RBDSQ, whereas in sample B the RBDSQ was administered during routine work-up. Conclusions: The diagnostic value of the RBDSQ strongly depends on the clinical setting and may be influenced by the individual's awareness on RBD. This finding is a critical issue which deserves clarification before use of this and other questionnaires can be recommended in epidemiological studies. (C) 2014 Elsevier B.V. All rights reserved.