Effect of a dual-boarded emergency-psychiatry physician on psychiatric consultations in the emergency department: A pre-post study in Japan.

Aim: To evaluate the impact of assigning a dual-boarded emergency-psychiatry physician to the emergency department (ED) on the frequency, timing, and nature of psychiatric consultations. Access to psychiatric evaluations in EDs is often limited, particularly in Japan, where general hospitals with psychiatric services are declining. Integrating dual-boarded physicians in emergency medicine and psychiatry may address unmet psychiatric needs. Methods: This retrospective, single-center, pre-post study was conducted at a secondary emergency hospital in Tokyo, Japan. All patients transported by ambulance between October 2020 and September 2024 were included in this study. An a priori sample size calculation was not performed; instead, the study size was determined by all consecutive eligible patients during this predefined observation period. The intervention involved the continuous assignment of a dual-boarded physician in October 2022. The primary outcome was the number of psychiatric consultations initiated by emergency physicians. Secondary outcomes included reasons for consultation, patient characteristics, physiological indicators at ED presentation, emergency procedures at admission, consultation setting, time from admission to consultation, and clinical outcomes; for patients with multiple consultations during the same hospitalization, only the initial consultation was analyzed. Results: Among 23,916 patients, 137 psychiatric consultations were analyzed. Consultations increased 3.41-fold post-intervention (31 vs. 106), with the consultation rate increasing from 0.29% to 0.81%. High-risk psychiatric presentations, including suicidal ideation (40.6% vs. 12.9%, p = 0.005), self-harm (42.5% vs. 19.4%, p = 0.019), and overdose (33.0% vs. 12.9%, p = 0.040), were significantly more common post-intervention, whereas delirium was less frequent (2.8% vs. 25.8%, p < 0.001). Vital signs at ED presentation and emergency procedures at admission were comparable between groups. Time from admission to consultation was shorter post-intervention (median 1 vs. 3 days, p = 0.007). The median hospital stay was also shorter from 22 to 8 days (p = 0.001). There was no significant change in the psychiatric hospital transfer rates. Conclusion: This study demonstrated that the 2-year assignment of one dual-boarded emergency-psychiatry physician was associated with an increased acceptance of more complex psychiatric cases in the ED, particularly those involving self-harm and suicidal ideation.