Validity of the Japanese version of the REM Sleep Behavior Disorder (RBD) Screening Questionnaire for detecting probable RBD in the general population

AimsIn order to evaluate the validity of the REM Sleep Behavior Disorder (RBD) Screening Questionnaire (RBDSQ) as a screening tool for RBD in a general population setting, we conducted a validation study using residents of a rural community. MethodsWe sent questionnaires that included the RBDSQ to 2631 eligible adult residents in the town of Daisen, Japan. ResultsOf those residents, 1572 participants (59.7%) gave complete answers to the RBDSQ. Among them, 179 participants (11.4%) scored 5 points on the questionnaire; an additional 149 participants scoring 4 points were randomly selected for further telephone interview. Based on obtained results, nine participants (0.57%) were judged as having probable RBD. Receiver-operator curve analysis revealed that a total score of 6 points on the RBDSQ represented the best cut-off value for detecting probable RBD (sensitivity: 100%; specificity: 73.0%). Analysis based on the item response theory revealed that items 1, 4, 6-1, 7, and 8 had lower difficulty than the remaining items, suggesting that these items are more essential in the screening for probable RBD. ConclusionsThe present study revealed that a score of 6 points on the RBDSQ could be used as a cut-off value for the screening of probable RBD in the general population. Evaluation of the distribution of positive items might be helpful for identifying the intensity of a person's RBD symptoms.