AKI Linked to Increased Mortality and Rehospitalization, With or Without CKD

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Patients hospitalized with acute kidney injury (AKI) are at elevated risk of rehospitalization and death, whether or not they have chronic kidney disease (CKD), reports a study in the American Journal of Kidney Diseases.

The analysis included 471,176 patients with a discharge diagnosis of AKI, propensity score-matched to the same number of patients hospitalized without AKI. Patients were identified from a national claims database (Optum Clinformatics). All were continuously enrolled throughout a 2-year lookback period, during which they were free of AKI hospitalization.

All-cause and selected-cause rehospitalization and mortality were assessed at 90 and 365 days after hospitalization, including possible interactions between AKI and pre-existing CKD. Fifty-one percent of patients hospitalized with AKI were men; the mean age was 73 years. Before index hospitalization, approximately 56% of patients had CKD, 47% had coronary artery disease, and 42% had diabetes.

On propensity score-matched analysis, AKI was associated with an increased rate of all-cause rehospitalization within 90 days: hazard ratio (HR), 1.62. Analysis of specific causes showed significant increases for end stage kidney disease: HR, 6.1; heart failure: HR, 2.81; sepsis: HR, 2.62; pneumonia: HR, 1.47; myocardial infarction: HR, 1.48; and volume depletion: HR, 1.64. Similar patterns were found for 365-day rehospitalization.

All-cause mortality was more than doubled for the AKI group: HR, 2.66 at 90 days and 2.11 at 365 days. Associations of AKI with rehospitalization were similar for patients with and without CKD. The association with mortality was weaker in patients with CKD.

The findings lend new insights into short- and long-term risk of adverse outcomes of AKI in a diverse US patient population. Rehospitalization and mortality risks are elevated at 3 months and 1 year after discharge for patients with AKI compared with matched patients without AKI. “[T]hese results underscore the immediate need for close posthospitalization monitoring of individuals with AKI,” the researchers write [Schulman IH, et al. Readmission and mortality after hospitalization with acute kidney injury. Am J Kidney Dis, published online ahead of print April 19, 2023. doi: 10.1053/j.ajkd.2022.12.008; https://www.ajkd.org/article/S0272-6386(23)00067-7/fulltext].