Acute kidney injury in heart failure hospitalization: a national study of outcomes and healthcare utilization.

BACKGROUND

Acute kidney injury (AKI) is a common complication among patients hospitalized with acute heart failure and is associated with worse clinical outcomes. However, contemporary national data examining its epidemiology and association with outcomes across heart failure phenotypes and chronic kidney disease (CKD) stages remain limited. We evaluated the prevalence of AKI and its association with mortality, critical care interventions, and healthcare utilization in a nationally representative cohort.

METHODS

We conducted a retrospective study using the 2022 Healthcare Cost and Utilization Project National Inpatient Sample. Adult hospitalizations for acute heart failure were identified using ICD-10-CM codes, and AKI was defined using diagnosis codes. Survey-weighted multivariable logistic regression models were used to identify factors associated with AKI and evaluate its association with in-hospital outcomes. Multicollinearity was assessed using variance inflation factors.

RESULTS

Among 1,126,036 hospitalizations, AKI occurred in 35.2%. AKI was associated with higher in-hospital mortality (adjusted odds ratio [aOR] 3.69; 95% CI 3.60-3.77), corresponding to adjusted mortality of 10.2% vs 3.4% (absolute difference 6.8% points). AKI was also associated with higher odds of mechanical ventilation (aOR 3.86), vasopressor use (aOR 3.66), and acute kidney replacement therapy (aOR 16.17) (all p < 0.001). In addition, AKI was associated with greater healthcare utilization, including prolonged length of stay (aOR 1.77; 40.0% vs 22.1%) and increased likelihood of discharge to skilled nursing or rehabilitation facilities (aOR 1.43).

CONCLUSIONS

AKI is common among acute heart failure hospitalizations and is associated with higher mortality, greater use of critical care interventions, and increased healthcare utilization. These findings reinforce prior evidence that AKI identifies a high-risk population. Given the observational design, results should be interpreted as associations rather than causal effects. Further studies using laboratory-based definitions and longitudinal outcomes are needed to better characterize the long-term implications of AKI.