Effects of transient acute kidney injury, persistent acute kidney injury and acute kidney disease on the long-term renal prognosis after an initial acute kidney injury event.

AIM: To clarify the effects of the duration of acute damage and/or loss of renal function following an acute kidney injury event on the renal prognosis after recovery.

METHODS: We retrospectively reviewed data collected between 1995 and 2016 from the Kochi Medical School Hospital. Patients were stratified according to the time required for recovery with fluid therapy (expected to reflect the presence of renal dysfunction): ≤2 days after onset, transient injury group (n = 491); 3 to 7 days after onset, persistent injury group (n = 1076); and ≥ 8 days after onset, acute kidney disease group (n = 1046). The healthy group comprised 1000 randomly selected adult patients without acute kidney injury with at least two creatinine measurement results during the study. Survival time was defined as the time from recovery to a 30% decrease in the estimated glomerular filtration rate (primary endpoint). Kaplan-Meier and Cox proportional hazards analyses were conducted.

RESULTS: Event incidence rates were higher for the transient injury, persistent injury and acute kidney disease groups than for the healthy group. Persistent injury and acute kidney disease presented a higher risk of renal function decline than transient injury following recovery.

CONCLUSION: Transient acute kidney injury, persistent acute kidney injury and acute kidney disease resulted in functional decline and rapid chronic kidney disease progression risks despite recovery. Transient acute kidney injury recovery within 2 days could be associated with better long-term prognoses than persistent acute kidney injury and acute kidney disease persisting beyond 2 days.