Acute Kidney Injury and Mortality in Cirrhosis: A Nationwide Analysis of Clinical Outcomes, Resource Utilization, and Effect Modification

Background Acute kidney injury (AKI) is a common complication in patients with cirrhosis and is associated with poor outcomes. However, contemporary national data quantifying the impact of AKI severity on mortality and healthcare utilization, as well as potential effect modification across patient subgroups, remain limited. Methods We conducted a retrospective cohort study using the 2023 Nationwide Inpatient Sample. Adult hospitalizations with cirrhosis were identified using ICD-10-CM codes. AKI was categorized as no AKI, non–dialysis-requiring AKI, and dialysis-requiring AKI (AKI-D). Survey-weighted multivariable regression models evaluated associations between AKI and in-hospital mortality, length of stay (LOS), and hospital costs. Sensitivity analyses and interaction testing by age and chronic kidney disease (CKD) were performed. Results A total of 70,219 unweighted hospitalizations, representing approximately 351,095 nationally, were included. AKI occurred in 32.6% of hospitalizations. In-hospital mortality was higher among patients with AKI compared with those without AKI (13.0% vs 2.5%, p < 0.001). In adjusted analyses, non–dialysis-requiring AKI was associated with increased mortality (adjusted odds ratio [OR] 4.34, 95% CI 3.99–4.72), while AKI-D was associated with markedly higher mortality (OR 16.37, 95% CI 14.18–18.91). AKI was also associated with increased LOS (ratio 1.45 for non-dialysis AKI; 2.78 for AKI-D) and higher hospital costs (ratio 1.43 and 3.75, respectively). Findings were consistent across multiple sensitivity analyses. Significant interactions were observed by CKD and age, with stronger relative effects in patients without CKD and in younger individuals (p for interaction < 0.001). Conclusions AKI is common among hospitalized patients with cirrhosis and is strongly associated with increased mortality and healthcare utilization, with a clear graded relationship by severity. The impact of AKI varies across patient subgroups, highlighting the importance of individualized risk assessment. Strategies targeting early recognition and prevention of AKI may improve outcomes and reduce healthcare burden in this population.