Acute kidney injury (AKI) is associated with progression to advanced chronic kidney disease (CKD). We tested whether patients who survive AKI and are at higher risk for CKD progression can be identified during their hospital admission, thus providing opportunities to intervene. This was assessed in patients in the Department of Veterans Affairs Healthcare System hospitalized with a primary diagnosis indicating AKI (ICD9 codes 584.xx). In the exploratory phase, three multivariate prediction models for progression to stage 4 CKD were developed. In the confirmatory phase, the models were validated in 11,589 patients admitted for myocardial infarction or pneumonia during the same time frame that had RIFLE codes R, I, or F and complete data for all predictor variables. Of the 5351 patients in the AKI group, 728 entered stage 4 CKD after hospitalization. Models 1, 2, and 3 were all significant with ‘c' statistics of 0.82, 0.81, and 0.77, respectively. In model validation, all three were highly significant when tested in the confirmatory patients, with moderate to large effect sizes and good predictive accuracy (‘c' 0.81–0.82). Patients with AKI who required dialysis and then recovered were at especially high risk for progression to CKD. Hence, the severity of AKI is a robust predictor of progression to CKD.

When patients develop acute kidney injury, a small fraction of them will develop end-stage renal disease later. The severity of renal impairment in the remaining patients is uncertain because studies have not carefully examined renal function over time or the precise timing of entry into a late stage of chronic kidney disease. To determine these factors, we used a United States Department of Veterans Affairs database to ascertain long-term renal function in 113,272 patients. Of these, 44,377 had established chronic kidney disease and were analyzed separately. A cohort of 63,491 patients was hospitalized for acute myocardial infarction or pneumonia and designated as controls. The remaining 5,404 patients had diagnostic codes indicating acute renal failure or acute tubular necrosis. Serum creatinine, estimated glomerular filtration rates, and dates of death over a 75-month period were followed. Renal function deteriorated over time in all groups, but with significantly greater severity in those who had acute renal failure and acute tubular necrosis compared to controls. Patients with acute kidney injury, especially those with acute tubular necrosis, were more likely than controls to enter stage 4 chronic kidney disease, but this entry time was similar to that of patients who initially had chronic kidney disease. The risk of death was elevated in those with acute kidney injury and chronic kidney disease compared to controls after accounting for covariates. We found that patients who had an episode of acute tubular necrosis were at high risk for the development of stage 4 disease and had a reduced survival time when compared to control patients.

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