**6. Conclusion**

We have described screening methods for RBD as well as some of the available RBD screening questionnaires. All of the questionnaires had high sensitivity in screening for RBD, but lower specificity. There were some problems and limitations related to these instruments. These validation studies were mainly performed in middle aged and elderly subjects. Therefore, validation of RBD screening questionnaires should be done in younger people. In the case of self-reported questionnaires, information from a bed partner is useful in achieving higher sensitivity and specificity for the instrument. Boeve suggested that the MSQ likely to be more appropriate for use in those with cognitive impairment/dementia since the responses are provided by bed partners (Boeve, 2010a). In any of the instruments that might be applied but are unable or unwilling to undergo PSG, or who have little or no apparent REM sleep during PSG, then a diagnosis of probable RBD would be justified (Boeve, 2010a). OSAS may represent a confounding factor in the clinical diagnosis of RBD (Comella et al., 2002). To differentiate RBD from OSAS, simultaneously screening for OSAS by pulse oxymetry may be useful. It is impractical to frequently perform PSG and the availability of PSG is often limited. Therefore, it is important to evaluate and follow up the severity of RBD through instruments such as RBDQ-HK. It is also necessary to develop a severity index for RBD. Tachibana recently developed an RBD severity index (RBDSI) in Japanese (Tachibana, 2009).

In conclusion, RBD questionnaires may be applied within a stepwise diagnostic process (questionnaire, interview, polysomnography) for RBD (Table 5).


Table 5. Diagnostic process for RBD
