Brief CommunicationThe REM sleep behavior disorder screening questionnaire: Validation study of a Japanese version
Introduction
REM sleep behavior disorder (RBD) is characterized by dream-enacting behaviors and vivid, action-filled or unpleasant dreams and presents a risk for self-injury and harm to others due to abnormal REM sleep during which control of muscle tonus is lacking [1]. Polysomnography (PSG) is required to establish the diagnosis and represents the diagnostic gold standard for revealing loss of REM-related muscle atonia with excessive amounts of sustained or intermittent elevation of submental EMG tone or excessive phasic submental or limb EMG twitching [1].
Recently, a specific screening scale for assessment of RBD, the RBD screening questionnaire (RBDSQ), was validated [2]. This study aimed to validate the Japanese version of the RBDSQ (RBDSQ-J) in a setting different from that used originally.
Section snippets
Methods
The objectives of this study were explained to the patent owner of the original version of the RBDSQ [2], and approval was given to translate the original version into Japanese to establish the first RBDSQ-J. Next, we asked a professional translator, who was not a medical provider, to back-translate the Japanese version into English. Then, we asked the authors of the original RBDSQ to confirm that the back-translated English document was equivalent to the original version in content and
Statistical analysis
Sample means of the RBDSQ-J total score in the iRBD, OSAS and healthy groups were compared by the Mann–Whitney U test. Sensitivity and specificity for different cut-off points were calculated and presented by means of a ROC function. The diagnostic value of the RBDSQ-J was calculated by the area under the curve (AUC), which is independent of an arbitrary choice of a cut-off point and tested for statistical significance using the Mann–Whitney U test. As a measure of reliability of the
Results
The mean RBDSQ-J score in the entire iRBD group was 7.5 ± 2.8 (range 1–12) points, with a score of 7.8 ± 2.8 (range 1–12) points for men and 6.9 ± 2.7 (range 2–12) points for women (P < 0.0001, respectively). This is in comparison with the entire OSAS group, which had a score of 1.9 ± 2.3 (range 0–11) (2.1 ± 2.6 [range 0–11] points for men and 1.5 ± 1.0 [range 0–3] points for women) (P < 0.0001, respectively). The mean score for the healthy subjects was 1.6 ± 1.2 (range 0–6) points, with a score of 2.1 ± 2.6
Discussion
Sensitivity and specificity using a cut-off of 4.5 were high in differentiating the iRBD group from healthy subjects or the OSAS group. Therefore, a cut-off of 5.0 was considered useful for differentiating the iRBD group from healthy subjects or the OSAS group. The original instrument, the RBDSQ, could discriminate RBD patients from healthy controls with a sensitivity of 96% and specificity of 56% at a cut-off level of 5.0 [2].
The mean original RBDSQ score in the RBD group was 9.5 ± 2.8 points [2]
Acknowledgments
The authors thank Dr. K. Stiasny-Kolster (Department of Neurology, Center of Nervous diseases, Philips-University, Marburg, Germany) for permission to develop a Japanese version of the instrument and for her helpful comments. The authors thank T. Sairenchi (Department of Public Health, Dokkyo Medical University) for his valuable suggestions concerning statistical analysis.
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