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

Abstract

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. The purpose of our study was to evaluate chest CT findings in patients receiving 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 [SD] years) receiving ICI therapy who underwent chest CT at 163 ED visits between 2011 and 2018. 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 was evaluated using kappa coefficients. Associations between CT findings and clinical parameters were explored using Fisher 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. The 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%). The most common CT pneumonitis pattern was radiation recall pneumonitis (6/21, 28.6%). A total of 78.5% of ED visits with chest CT resulted in hospitalization; 66.9% of patients subsequently died. Survival was worse for patients with, versus without, worsening tumor (72.2% vs 49.1% of patients deceased vs alive at follow-up, p = .006) and for patients with, versus without, pleural effusion (39.2% vs 17.5% of patients deceased vs alive at follow-up, p = .04). Kappa values for interreader agreement of evaluated chest CT findings ranged from 0.66 (worsening tumor burden) to 1.00 (numerous findings). CONCLUSION. Most ED chest CT examinations in patients receiving 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. Understanding pathologies detected on chest CT in patients undergoing ICI therapy who present to the ED may guide radiologists in interpreting such imaging.

Keywords: emergency radiology; immune checkpoint inhibitors; immune-related adverse events; immunotherapy; pneumonitis.