Prevalence and Clinical Correlates of Probable REM Sleep Behavior Disorder in Psychiatric Sleep Clinic Outpatients: A Retrospective Study

Objective: This study aimed to investigate the prevalence of probable REM sleep behavior disorder (pRBD) and identify associated factors among psychiatric sleep clinic outpatients. Methods: We retrospectively reviewed records of first-visit outpatients aged ≥18 years who presented with sleep-related complaints at the psychiatric sleep clinic at a single tertiary university hospital between January 1, 2023, and December 31, 2024. Of 522 patients, 387 (74.1%) completed the REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ), and 356 were included in the analysis. RBDSQ scores ≥5 defined the pRBD group. Demographic and clinical variables, including diagnoses and medication use, were collected. Univariable and multivariable logistic regression analyses identified factors associated with pRBD. Results: Among participants, 179 (50.3%) were classified as pRBD and 177 (49.7%) as non-RBD. The pRBD group was significantly younger, had a higher body mass index, and showed higher scores for insomnia, depression, anxiety, and trauma exposure, and risk of obstructive sleep apnea (OSA). They were also more likely to be diagnosed with trauma- and stressor-related disorders and selective serotonin reuptake inhibitors (SSRIs). In multivariable analysis, higher anxiety scores (odds ratio [OR]=1.07, 95% confidence interval [CI]=1.02–1.12), sleep-related breathing disorders (OR=7.60, 95% CI=2.05–28.17), and SSRIs use (OR=6.91, 95% CI=1.91–22.11) were independently associated with pRBD. Conclusion: RBD symptoms were common among psychiatric sleep clinic outpatients. These results suggest that psychiatric patients with marked anxiety, SSRIs use, and sleep-related breathing disorders should be prioritized for screening, particularly before antidepressant initiation, with careful differentiation from OSA.