Emergency Department Utilization for Patients Receiving Immune Checkpoint Inhibitors: A Retrospective Analysis of Identification and Outcomes for Those Presenting for Immune-Related Adverse Events

BACKGROUND: Immune-related adverse events (iRAEs) are known complications of immune checkpoint inhibitors (ICIs). Early identification and management leads to improved morbidity and mortality. This study seeks to address our center's experience with iRAEs in the emergency department (ED). METHODS: We performed a retrospective review of patients treated with ICIs in 2018 and 2019 for any indication. All diagnoses of iRAEs were recorded. For all patients who presented to the ED following administration of an ICI, we assessed whether the presenting symptoms were eventually diagnosed as an iRAE. We assessed disposition, time to initiation of corticosteroids and outcomes in these patients. RESULTS: 351 evaluable patients were treated with an ICI, 129 patients (37%) had at least one presentation to the ED, 17 of whom presented with symptoms due to a new iRAE. New iRAE diagnoses were broad, occurred after median 2 cycles, majority irAEs were grade 3 or higher (70.6%), and two patients died due to toxicity. Twelve patients were admitted to the hospital during initial presentation or at follow-up, four required ICU care. All patients required immunosuppressive therapy, and only three were later re-challenged with an ICI. Of the patients who were admitted to the hospital, median time to first dose of corticosteroid was 30.5 h (range 1-269 h). CONCLUSIONS: Patients on ICI have a significant risk of requiring an ED visit. A notable proportion of iRAEs have their first presentation at the ED and often can present in a very nonspecific manner. A standardized approach in the ED at the time of presentation may lead to improved identification and management of these patients.