Diagnostic quantitative thresholds for rapid eye movement sleep without atonia in Japanese patients with isolated...

This study aims to clarify the diagnostic cutoff values of rapid eye movement sleep without atonia (RWA) for identifying isolated rapid eye movement sleep behavior disorder (iRBD) in Japanese population. We will analyze these cutoff values according to the established methods and explore their validity with clinical and neurophysiological markers.

We analyzed RWA in 79 patients with clinical iRBD and 59 age-, sex-, PLMS-, apnea hypopnea index-matched controls. Cutoff values for diagnosing iRBD for phasic RWA in the submental (SM) and limbs, tonic RWA in the SM, and a combination of any RWA in the SM and phasic RWA in the flexor digitorum superficialis were calculated. In patients with iRBD, clinical and neurophysiological markers were compared between groups categorized by the existing cutoff level and the newly defined level in this study.

Optimized and maximized specificity diagnostic cutoffs for iRBD were: 9.4% and 15.6% in phasic RWA in the SM and limbs (area under the curve [AUC] = 0.992), 0.94% and 11.9% in tonic RWA in SM (AUC = 0.912), and 11.3% and 11.3% in combination of any RWA in the SM and phasic RWA in the flexor digitorum superficialis (AUC = 0.973). Clinical and neurophysiological markers were mostly not different between the groups categorized by the previous and current cutoff values.

A lower RWA cutoff for diagnosing iRBD was identified in Japanese individuals compared to Western populations, though the clinical significance of this difference was minimal. Statement of Significance Numerous methods for polysomnographically evaluating rapid eye movement sleep behavior disorder (RBD) have been reported, and their diagnostic accuracy has been already established. However, specific diagnostic cutoff values for the Sleep Innsbruck Barcelona and the American Academy of Sleep Medicine methods for Asian individuals have not yet been established. This study aimed to determine the diagnostic cutoff values for both scoring methods within a cohort of Japanese iRBD patients and healthy controls. The findings suggest that the cutoff values for Asians are lower than those for Western populations. This distinction should be considered when diagnosing isolated RBD in Asia.