Findings Suggest Kidney Disease Observed after Acute Kidney Injury Often Present Before Injury 

A UC San Francisco (UCSF)-led study of patients with chronic kidney disease (CKD) has found that mild-to-moderate acute kidney injury (AKI) did not predict worsening of kidney function after taking into account differences in pre-existing health. Instead, the research suggests that much of the kidney disease observed after AKI may already be present before AKI.   

The presence of AKI has often been understood to be an independent risk factor for accelerated loss of kidney function and many nephrologists now believe that AKI causes acceleration of CKD progression. This has led to changes in research focus, practice patterns, and public health targets. Prior studies associating AKI with more rapid subsequent loss of kidney function had methodological limitations, including inadequate control for differences between patients who had AKI and those who did not. 

"Our study more rigorously addressed methodological limitations presented in prior studies,” said Anthony Muiru, MD, MPH, UCSF nephrologist and first author of the study. “Because of this, we were able to conclude that the independent association between mild to moderate AKI and worsening subsequent kidney function trajectory appears to be small.”  

The findings published July 10, 2023, in Annals of Internal Medicine, indicate that efforts focused on ameliorating the effects of an AKI episode may have only a small effect on overall CKD burden.  

The researchers studied 3,150 people with CKD to determine whether an AKI episode in the hospital is independently associated with subsequent kidney outcomes. A total of 612 AKI episodes were observed in 433 persons with CKD over a median follow-up of 3.9 years. After adjusting for patient characteristics, such as the level of proteinuria (protein in the urine), mild to moderate AKI did not predict worsening of subsequent kidney function trajectory.  

The research results suggest that much of the kidney disease progression observed after AKI may already be present before AKI. They recommend that clinicians instead focus treating proteinuria before the AKI episode. The authors acknowledge, however, that a diagnosis of AKI does present an opportunity to identify high-risk patients and implement evidence-based interventions to slow CKD progression.    

“These results from the prospective Chronic Renal Insufficiency Cohort (CRIC) study challenge the paradigm that all AKI episodes lead to worse kidney outcomes and highlight the importance of knowing a patient’s long-term trajectory of kidney function before being hospitalized,” said Alan S. Go, MD, associate director of the Kaiser Permanente Northern California Division of Research and one of the CRIC study authors.

 

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