Changing epidemiology and outcomes of acute kidney injury in hospitalized patients with cirrhosis - a US population-based study

Background & aims: Acute kidney injury (AKI) is a significant clinical event in cirrhosis yet contemporary population-based studies on the impact of AKI on hospitalized cirrhotics are lacking. We aimed to characterize longitudinal trends in incidence, healthcare burden and outcomes of hospitalized cirrhotics with and without AKI using a nationally representative dataset.

Methods: Using the 2004-2016 National Inpatient Sample (NIS), admissions for cirrhosis with and without AKI were identified using ICD-9 and ICD-10 codes. Regression analysis was used to analyze the trends in hospitalizations, costs, length of stay and inpatient mortality. Descriptive statistics, simple and multivariable logistic regression were used to assess associations between individual characteristics, comorbidities, and cirrhosis complications with AKI and death.

Results: In over 3.6 million admissions for cirrhosis, 22% had AKI. AKI admissions were more costly (median $13,127 [IQR $7,367-$24,891] vs. $8,079 [IQR $4,956-$13,693]) and longer (median 6 [IQR 3-11] days vs. 4 [IQR 2-7] days). Over time, AKI prevalence doubled from 15% in 2004 to 30% in 2016. CKD was independently and strongly associated with AKI (adjusted odds ratio 3.75; 95% CI 3.72-3.77). Importantly, AKI admissions were 3.75 times more likely to result in death (adjusted odds ratio 3.75; 95% CI 3.71-3.79) and presence of AKI increased risk of mortality in key subgroups of cirrhosis, such as those with infections and portal hypertension-related complications.

Conclusions: The prevalence of AKI is significantly increased among hospitalized cirrhotics. AKI substantially increases the healthcare burden associated with cirrhosis. Despite advances in cirrhosis care, a significant gap remains in outcomes between cirrhotics with and without AKI, suggesting that AKI continues to represent a major clinical challenge.

Lay summary: Sudden damage to the kidneys is becoming more common in people who are hospitalized and have cirrhosis. Despite advances in cirrhosis care, those with damage to the kidneys remain at higher risk of dying.