Acute kidney injury (AKI) — even when it resolved quickly — was tied to poorer long-term renal outcomes in a prospective cohort study.
People who experienced non-resolving AKI saw more than a two-fold higher risk for a major adverse kidney event (MAKE) compared with those who didn’t have AKI (adjusted hazard ratio 2.30, 95% CI 1.52-3.48, P<0.001), reported Pavan Bhatraju, MD, MSc, of the University of Washington in Seattle, and colleagues.
Even those whose kidney function resolved within 72 hours after a diagnosis of AKI also had a 52% higher risk for a long-term MAKE compared with those with AKI (aHR 1.52, 95% CI 1.01-2.29, P=0.04), according to the study online in JAMA Network Open.
However, when the researchers compared cases of AKI, those whose AKI did not resolve saw a significantly higher rate of a MAKE -- a composite of progressive kidney disease, need for long-term dialysis, or all-cause mortality (aHR 1.51, 95% CI 1.22-1.88, P<0.001) compared with those whose AKI resolved.
These associations were adjusted for demographic factors like age, sex, and race, as well as for clinical factors including diabetes status, chronic kidney disease status, cardiovascular disease, and sepsis. The associations were also still significant after the group controlled for the magnitude of increased serum creatinine concentrations -- or the AKI stage -- in those who recovered from their AKI. Nearly three-quarters of those with AKI had injury classified as stage 1.
"The use of AKI recovery subgroups to risk stratify patients with AKI we believe is clinically intuitive," Bhatraju's group wrote.
The observational study included 1,538 hospital patients: half of whom did not experience AKI, 31% of whom had resolving AKI, and 19% who had non-resolving AKI within 3 months of admission.
AKI was defined according to standard diagnostic criteria: an increase in serum creatinine concentration of 50% or more or 0.3 mg/dL or more above an outpatient, non-emergency department baseline value within 7 to 365 days prior to the initial hospital admission. AKI that resolved was considered to be a decrease in serum creatinine concentration of 0.3 mg/dL or more or at least 25% from maximum within the initial 72 hours following an AKI diagnosis.
During median follow-up of 4.7 years, 36% of the entire cohort had a MAKE.
"[These findings] provide evidence for considering the timing of functional recovery from AKI as a factor associated with future adverse events," Ravindra Mehta, MBBS, MD, DM, of the University of California San Diego, said in an accompanying commentary. He also noted that while these findings highlight the value of using AKI recovery pattern to predict long-term kidney outcomes, the study simultaneously underscores how current AKI staging criteria was not helpful in predicting these outcomes "as the severity stage by itself did not differentiate among which patients would develop MAKE."
"It is ... clear that clinicians managing patients with AKI should consider the severity of the disease and the ensuing course and tailor their diagnostic and therapeutic interventions to facilitate rapid and complete recovery of kidney function," he concluded.