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

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.