Association of acute kidney injury with in-hospital mortality and resource utilization among U.S. solid tumor hospitalizations: A National Inpatient Sample analysis, 2018–2022.

e23163 Background: Acute kidney injury (AKI) is a common and clinically significant complication among patients hospitalized with cancer. Despite its known impact on outcomes, contemporary national data evaluating the association between AKI, inpatient mortality, and healthcare resource utilization among hospitalizations primarily for solid tumors remain limited. This study aimed to assess the relationship between AKI and in-hospital mortality, length of stay, and resource utilization in cancer-related hospitalizations at a national level. Methods: A retrospective, hospitalization-level cohort study was conducted using the Healthcare Cost and Utilization Project National Inpatient Sample (NIS) from 2018 to 2022. Adult hospitalizations with a principal diagnosis of solid tumor malignancy were identified using ICD-10-CM diagnosis codes, excluding hematologic malignancies. AKI was defined by the presence of ICD-10-CM code N17* in any diagnosis position. Analyses accounted for the complex NIS survey design using discharge-level weights, hospital clustering, and stratification variables to generate nationally representative estimates. Primary outcomes included in-hospital mortality, length of stay (LOS), and total hospitalization charges. Results: An estimated 4,298,089 hospitalizations with a principal diagnosis of solid tumor malignancy were identified (95% CI 4,197,740–4,398,438), of which 13.49% (95% CI 13.35%–13.62%) were complicated by AKI. In-hospital mortality was higher among hospitalizations with AKI compared with those without AKI (12.30% [95% CI 12.08%–12.53%] vs 2.78% [95% CI 2.65%–2.91%]; absolute difference 9.52%). Hospitalizations complicated by AKI had longer mean LOS (9.71 days [95% CI 9.63–9.79]) than those without AKI (5.58 days [95% CI 5.54–5.61]; difference 4.13 days). Mean total hospitalization charges were also higher in the AKI group ($138,994 [95% CI $136,177–$141,811]) compared with hospitalizations without AKI ($93,009 [95% CI $91,489–$94,529]; difference $45,985). Conclusions: In a nationally representative sample of U.S. hospitalizations primarily for solid tumors, AKI was common and was associated with higher in-hospital mortality, longer hospitalization, and substantially greater resource utilization. These findings underscore the significant inpatient burden associated with AKI in oncology populations and support the importance of hospitalization-level risk stratification and system-based strategies aimed at mitigating kidney-related complications during cancer care.