To validate an emergency room (ER) pathway that risk-stratifies youths with first-episode psychosis (FEP) according to the likelihood of secondary etiologies, inclusive of autoimmune encephalitis (AE), and guides evaluation for low and high-risk patients.

Rates of ER visits for psychosis are rising at alarming rates, particularly among youths. Rarely, psychosis is the sole presenting feature of AE. While early AE detection and treatment are critical, invasive testing and overdiagnosis can lead to harm. There is thus a growing need for tools to differentiate between FEP due to primary psychiatric versus secondary neuroimmunologic causes in the acute care setting.

An interdepartmental pathway was developed through collaboration between our neurology, psychiatry and emergency departments. Patients under 22 years old presenting to the ER with FEP were prospectively enrolled. Pathway entry required FEP verification by psychiatry. Enrolled patients were risk-stratified according to the presence or absence of predetermined red-flag signs and results of initial tests: brain magnetic resonance imaging and serum studies. The pathway directed the role and timing of neurologic consultation and additional evaluation (including lumbar puncture [LP] and electroencephalogram [EEG]) according to level of risk.

Thirty-five patients were prospectively enrolled over a 19-month period. Nineteen (54%) had atypical psychiatric symptoms. Brain MRI and serum AE panels were performed in 33 (94%) and 29 (83%) of patients respectively, but none of these findings were clinically significant. Per the pathway’s algorithm, none of the enrolled patients required an LP or EEG. None were found to have a neuroimmunologic or other secondary etiology of FEP (negative predictive value = 100%).

To our knowledge, this is the first interdepartmental diagnostic algorithm used in practice to triage youths with psychiatrist-confirmed FEP in the ER setting. Feasibility, validity and clinical utility were demonstrated.