Hospital-Acquired Acute Kidney Injury (AKI) Ups Early Readmission Risk

Researchers observe a significant 21% increased odds of rehospitalization within 30 days.
Researchers observe a significant 21% increased odds of rehospitalization within 30 days.

Patients who suffer hospital-acquired acute kidney injury (AKI) are at higher risk of early hospital readmission, according to a new study.

Investigators led by Bertrand L. Jaber, MD, MS, of Tufts University School of Medicine in Boston, studied 22,001 hospitalized adults, of whom 3,345 (15%) experienced AKI during the index hospitalization. The 30-, 60-, and 90-day hospitalization rates were 15%, 20%, and 23%, respectively, for the AKI patients compared with 11%, 15%, and 18% for the non-AKI patients, respectively.

In adjusted analyses, the AKI patients had a significant 21%, 15%, and 13% increased odds of readmission within 30, 60, and 90 days, respectively, compared with non-AKI patients, the researchers reported online ahead of print in the American Journal of Kidney Diseases.

In a propensity score–matched cohort of 5,912 patients, Dr. Jaber's group found that AKI was associated with a significant 16% increased odds of readmission within 30 days and a non-significant 11% and 8% increased odds at 30 and 90 days, respectively.

The AKI group was more likely to be rehospitalized within 30 days for cardiovascular-related conditions, particularly heart failure and myocardial infarction.

 “Our study suggests that AKI might be an unrecognized determinant of short-term hospital readmission and calls for the systematic study of transitions of care among hospitalized patients who experience an episode of AKI, with the ultimate goal of preventing or decreasing unplanned rehospitalizations,” the authors wrote.

The researchers concluded that their study supports the hypothesis that mild forms of hospital-acquired AKI portend increased odds of hospital readmissions within 30 days. “Whether the relationship between hospital-acquired AKI and hospital readmission is causal or associative, AKI is a compelling risk factor for this unwarranted and costly outcome,” they wrote.

“If our findings are externally validated, the identification of mild episodes of hospital-acquired AKI should compel physicians to exercise heightened vigilance with a focus on timely follow-up of such patients in the ambulatory setting.”

Dr. Jaber and his colleagues acknowledged important study limitations. They noted that the study was conducted at a single acute-care facility, “so the generalizability of the results may be narrowed.” The researchers lacked information on socioeconomic status, which might have affected transitions to care services and hospital readmission risk.

Additionally, they pointed out that their hospital is not a trauma center, and consequently may treat patients with milder stages of AKI.

In a previous study of 6,535 patients hospitalized with heart failure published in The American Journal of Cardiology (2012;109:1482-1486), researchers found that patients without chronic kidney disease (CKD) who experienced AKI had a significant 81% increased odds of readmission within 30 days compared with patients who had neither CKD nor AKI.

In that study, AKI occurred in 6.5% of patients during the index hospitalization, and 16% had CKD.

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