Incidence, risk factors, and mortality of acute kidney injury in patients receiving immune checkpoint inhibitors: analysis by acute kidney injury subtype

Background: Acute kidney injury (AKI) is a common complication in patients receiving immune checkpoint inhibitor (ICI) therapy. It can result from conventional causes or immune-mediated mechanisms. This study aimed to determine the incidence, risk factors, and clinical outcomes of all-cause AKI in patients treated with ICIs. Methods: We retrospectively analyzed adults treated with ICIs at Korea University Anam Hospital between 2015 and 2024. AKI occurring within 12 months after treatment initiation was defined according to the KDIGO (Kidney Disease: Improving Global Outcomes) criteria. It was classified as transient azotemia (recovery within 72 hours) or sustained AKI (>72 hours), including acute tubular necrosis (ATN), obstruction, and ICI-associated AKI (ICI-AKI). Results: Among 943 patients, the overall incidence of AKI was 32.1%. ATN was most common, followed by transient azotemia, obstruction, and immune-mediated acute tubulointerstitial nephritis. Pre-existing chronic kidney disease and proton pump inhibitor use were independent risk factors for immune-mediated AKI, whereas low serum albumin, high C-reactive protein, and hepatobiliary cancers were associated with ATN. Transient azotemia and ATN were independently associated with higher mortality. Although ICI-AKI was also significantly associated with increased mortality, the association was modest and should be interpreted cautiously given the limited number of cases (n = 25). Conclusion: ATN and transient azotemia were more frequent than ICI-AKI and were associated with worse prognosis; ICI-AKI also showed a statistically significant but modest association with mortality. Identifying different risk factors for each subtype may help clinicians achieve earlier recognition and optimize management in patients receiving ICI therapy.