Findings on Chest CT Performed in the Emergency Department in Patients on Immune Checkpoint Inhibitor Therapy: Single-Institution 8-Year Experience in 136 Patients.

Background. Patients undergoing immune checkpoint inhibitor (ICI) therapy may present to the emergency department (ED) with a wide range of immune-related adverse events. Objective. To evaluate chest CT findings in patients on ICI therapy presenting to the ED, and to explore these findings' associations with clinical parameters. Methods. This retrospective study included 136 patients (75 men, 61 women; mean age, 65±12 years) on ICI therapy with a total of 163 ED visits between 2011 to 2018 in which chest CT was performed. Two radiologists independently reviewed chest CT examinations for various findings and resolved discrepancies by consensus. Clinical parameters, including survival at last available follow-up, were recorded. Chest CT findings were summarized, and interreader agreement evaluated using kappa coefficients. Associations between CT findings and clinical parameters were explored using Fisher's exact, chi square, Wilcoxon, and Kruskal-Wallis tests. Results. A total of 62.5% of patients had primary lung cancer; 52.9% received nivolumab monotherapy, and 30.1% received pembrolizumab monotherapy. A total of 55.8% of ED visits occurred within 60 days after ICI initiation. Most common CT findings were worsening lung tumor burden (60.1%), new consolidation unrelated to tumor (30.1%), new or worsening pleural effusion (23.9%), and ICI-associated pneumonitis (12.9%). Most common CT pneumonitis pattern was radiation recall pneumonitis (6/21, 28.6%). A total of 78.5% of ED visits in which chest CT was performed resulted in hospitalization; 66.9% of the ED visits were associated with subsequent death. Survival was worse for examinations with, vs without, worsening tumor (72.2% vs 49.1% deceased, respectively; p=.006) and for examinations with, vs without, pleural effusion (39.2% vs 17.5% decreased, respectively; p=.04). Interreader agreement for evaluated chest CT findings ranged from kappa=0.66 (worsening tumor burden) to kappa=1.00 (numerous findings). Conclusion. Most chest CT examinations in the ED in patients on ICI therapy exhibited worsening lung tumor burden, which was associated with worse survival. New consolidation and ICI-associated pneumonitis (most commonly radiation recall pneumonitis) were also commonly detected in the ED setting. Clinical Impact. This knowledge of pathologies detected on chest CT in patients on ICI therapy who present to the ED may guide radiologists in interpreting such imaging.