The Kidney Disease: Improving Global Outcomes (KDIGO) guideline recommends kidney function evaluations at 3 months after acute kidney injury (AKI) for prognosis, but the findings are an “unreliable” indicator of kidney outcomes, according to investigators.

In the NARA-AKI study of 5272 Japanese patients undergoing surgery (not cardiac, obstetric, or urological), postoperative AKI within 7 days occurred in 316 (6%). At 3 months, creatinine-based estimated glomerular filtration rates (eGFR) indicated that kidney function was stable or increasing, but it declined afterward. The investigators calculated eGFR using the Japanese Society of Nephrology equation.

Among a subset of 938 patients without chronic kidney disease (CKD) at baseline or at 3 months, new-onset CKD developed in 226 patients, and 161 experienced a 30% or more decline in eGFR. AKI was significantly associated with a 1.7-fold increased risk of new-onset CKD and a 2.4-fold increased risk of a 30% or greater decline in eGFR after 3 months, Masatoshi Nishimoto, MD, PhD, and colleagues from Nara Medical University in Nara, Japan, reported in Nephrology Dialysis Transplantation.

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Dr Nishimoto’s team stated that regardless of normal creatinine-based eGFR values at 3 months, kidney function after AKI may be poor. “Thus recovery of serum creatinine to baseline values does not preclude the potential for permanent damage to the kidneys after AKI.”

The investigators noted that 3-month eGFR might be affected by illness-related loss of muscle mass. They suggested using measured creatinine clearance or possibly cystatin C-based eGFR rather than creatinine-based eGFR.

Among the study’s limitations, the investigators did not have information on patients’ comorbidities, postsurgical muscle loss, or changes in kidney function before surgery.


Nishimoto M, Murashima M, Kokubu M, et al. Kidney function at 3 months after acute kidney injury is an unreliable indicator of subsequent kidney dysfunction: the NARA-AKI cohort study. Published online May 11, 2022. Nephrol Dial Transplant. doi:10.1093/ndt/gfac172