Risk of intensive care unit admission after immune checkpoint inhibitor use in cancer

Immune checkpoint inhibitors (ICIs) have transformed cancer therapy but can cause excessive immune activation, leading to severe adverse events, including intensive care unit (ICU) admission. Existing evidence on critical illness after ICI use is limited, largely single center, and focused on immune related adverse events. This study evaluates the risk of inpatient and ICU admissions after ICI initiation using two large national databases. We retrospectively analyzed MarketScan Commercial and Multi-state Medicaid Research Databases (2016-2022) to identify adults with solid organ malignancies treated with ICIs and determined if ICU admission was required within 90 days of ICI administration. The primary diagnosis for ICU admission was identified and categorized. Associations between cancer type, ICI type, and ICU admission were analyzed. About 33,040 patients received ICIs during the study period. About 48.9% were male and 51.1% female. Pembrolizumab was the most used (49.3%), followed by nivolumab (31.9%), and ipilimumab (9.4%). Lung cancer was the most common malignancy (40.8%), followed by genitourinary (16%), melanoma (13%), gastrointestinal (12%), and breast (10%). About 22.0% (n = 7,216) of patients were hospitalized, and 8.7% (n = 2,872) required ICU admission. Infection was the most frequent reason for ICU admission, followed by respiratory causes. The odds of being admitted to the ICU were higher with combination ICI (OR = 1.51, P < .001) compared to ICI monotherapy. In conclusion, among patients with solid organ malignancies, nearly 9% required ICU admission within 90 days of ICI initiation, most commonly for infectious causes. These findings highlight the need for heightened vigilance for critical illness in patients treated with ICIs.