Retrospective analysis of hospital admissions due to immune checkpoint inhibitor‐induced immune‐related adverse events (irAE)

Aim Hospital admissions secondary to immune-related adverse events (irAE) arising from immune checkpoint inhibitors (ICI) are likely to increase with increasing use of this class of drug. We sought to determine the characteristics and outcomes of hospital admissions due to irAE. Methods A retrospective analysis of patients treated with ICI at two tertiary hospitals in Queensland (Australia) was performed. Patients who received at least one dose of ICI for a nonhaematological malignancy between the 1st January 2016 and 1st January 2017 were included. All subsequent hospital admissions were analyzed. Results A total of 140 patients were included, with the most common malignancies being non-small-cell-cell lung cancer (41%) and melanoma (18%), and most patients received anti-PD1 treatment (78%). A sum of 76 patients accounted for 116 admissions. Comparing admissions due to irAE and non-irAE, those admitted for irAE had a significantly longer duration on ICI prior to admission (173 vs 105 days, P = 0.04) but durations of admissions were similar (9.0 vs 8.5 days, P = 0.85). Fifteen patients (11% overall cohort) accounted for 18 admissions attributable to 16 separate irAE. irAE was not considered as a differential diagnosis on admission in 7 patients (38%). In those patients, commencement of corticosteroids was delayed (1.5 days, P = 0.01) but this did not translate into adverse outcomes such as prolonged admissions, prolonged steroid use or long-term complications. All patients with irAE were managed with high-dose corticosteroids. One death resulted from irAE (pneumonitis). Conclusions A sum of 11% patients receiving ICI required hospital admission for irAE. The relatively high rate of irAE as a missed differential diagnosis on admission suggests a need for improved cross-discipline awareness, education, and institutional management guidelines.