Acute kidney injury (AKI) is an independent risk factor for rehospitalization and death both in the short- and long-term, investigators reported at Kidney Week 2021, a virtual meeting of the American Society of Nephrology.

Ivonne H. Schulman, MD, program director in the Division of Kidney, Urologic, and Hematologic Diseases of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), and colleagues compared 594,509 patients hospitalized with AKI and 594,509 propensity-score matched patients hospitalized for other causes from the 2007-2020 Optum Clinformatics database, a demographically and geographically diverse population in the US with private insurance.

AKI was significantly associated with a 77% adjusted increased rate of any hospital readmission within 90 days of initial discharge compared with no AKI, the investigators reported. AKI was also significantly associated with a 1.6-, 3.1-, 3.2-, and 7.9-fold increased risk for pneumonia, sepsis, heart failure, and end-stage kidney disease, respectively, within 90 days of discharge.

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At 1 year, the cumulative incidence of all-cause rehospitalization was significantly higher in the AKI group. In the 2 years before the index admission, twice as many patients with AKI (55.9%) than without (26.5%) had been hospitalized.

All-cause mortality rates in the AKI group were a significant 3.0- and 2.4-fold higher at 90 days and 1 year, respectively, compared with the no-AKI group.

Pre-existing chronic kidney disease (CKD) was observed in half of patients and pre-existing heart failure in a third of patients in both groups. Analyses of patients with and without CKD yielded similar results.

In an interview with Renal & Urology News, Dr Schulman pointed out that sepsis, heart failure, and recurrent AKI – which were significantly more common in the AKI group – were the primary causes of rehospitalization within 90 days and 1 year.

“While the best post-AKI clinical management regimen is yet to be determined, these results underscore the immediate need for close post-hospitalization monitoring of individuals with AKI,” Dr Schulman said. “The NIDDK recently initiated the Caring for OutPatiEnts after Acute Kidney Injury (COPE-AKI) Consortium, which will develop and test interventions that aim to reduce short-term and long-term morbidity compared with usual care in patients after hospitalization with stage 2 and 3 AKI.”

[Editor’s note: Complete study findings were published in the American Journal of Kidney Diseases in April 2023]


Hernandez Schulman I, Anh Ngo D, Chan KL, et al. Readmission and mortality after AKI hospitalization. Presented at: Kidney Week 2021; November 2-7, 2021. Poster TH-OR06.