Early resolution of AKI leads to better long-term outcomes

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The first 72 hours after diagnosis of acute kidney injury (AKI) have a major impact on the long-term risk of kidney-specific outcomes, according to an analysis of prospective cohort data reported in JAMA Network Open.

The study included 1538 hospitalized patients from the prospective multicenter Assessment, Serial Evaluation, and Subsequent Sequelae of Acute Kidney Injury (ASSESS-AKI) study: 769 patients with AKI and 769 without. Participants were enrolled 3 months after hospital discharge between 2009 and 2015, with follow-up to 2018. The two groups were matched for demographic characteristics, hospital, comorbidity, and preadmission estimated glomerular filtration rate (eGFR).

About 62% of patients had “resolving AKI,” defined as a decrease in serum creatinine concentration of ≥ 0.3 mg/dL or at least 25% from the peak value, within 72 hours after AKI diagnosis. The main outcome of interest was a composite of major adverse kidney events (MAKE): occurrence or progression of chronic kidney disease (CKD), long-term dialysis, or death of any cause.

The patients were 964 men and 574 women, mean age 64.6 years. At a median follow-up time of 4.7 years, the MAKE primary outcome occurred in 36% of patients: incidence rate 5.9 events per 100 patient-years in the non-AKI cohort, 11.9 events per 100 patient-years in those with resolving AKI, and 16.6 events per 100 patient-years in those with nonresolving AKI.

The adjusted hazard ratio (HR) for MAKE was 1.95 for patients with resolving AKI and 2.80 in those with nonresolving AKI, compared with the non-AKI group. The associations persisted after further analysis for KDIGO stage at 72 hours, shock, mechanical ventilation, and major surgery: HR 1.52 and 2.30, respectively.

Among patients with AKI, the risk of MAKE was 51% higher for those with nonresolving AKI: HR 2.40 for incident CKD and 1.58 for progressive CKD. The two AKI groups were at similar risk for dialysis and death. Associations between AKI recovery pattern and MAKE were independent of hospital length of stay, vasopressor initiation, and serum creatinine concentration at discharge.

The trajectory of kidney recovery after AKI provides useful information on the risk of poor short-term outcomes. The new results suggest that hospitalized patients with early resolution of AKI have better long-term outcomes.

Patients whose AKI doesn’t resolve within the first 72 hours are at higher risk for MAKE, specifically incident and progressive CKD. Stratification by early recovery pattern may aid prognosis and targeting resources for follow-up and early detection of CKD [Bhatraju PK, et al. Association between early recovery of kidney function after acute kidney injury and long-term clinical outcomes. JAMA Network Open 2020; 3:e202682].