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Background. Acute kidney injury (AKI) requiring renal replacement therapy (RRT) is associated with high in-hospital morbidity and mortality in critically ill patients. Long-term outcomes have received little attention.

Methods. The aim of this study was to characterize AKI–chronic kidney disease (CKD) nexus in critically ill patients with AKI (RIFLE class F). We performed a single-centre prospective observational study of 425 consecutive critically ill patients with AKI requiring RRT. None of these patients had pre-existing kidney disease. Primary outcomes were vital status and renal function at hospital discharge and at 5 and 10 years of follow-up.

Results. The overall in-hospital mortality of the study cohort was 47%, the mortality rates at 1, 5 and 10 years were 65, 75 and 80%, respectively. At hospital discharge, recovery of renal function was complete in 56% of survivors. None of these patients developed CKD during follow-up. Ninety percent of the 100 survivors with partial recovery of renal function had ongoing CKD during long-term follow-up. CKD progressed to end-stage renal disease (ESRD) in 12 patients (3% of the cohort or 5% of survivors). The patients with post-AKI CKD had a higher prevalence of hypertension, a higher rate of fatal cardiac diseases and a higher all-cause death rate.

Conclusion. Long-term survival of critically ill patients with AKI requiring RRT is poor and determined by the development of de novo CKD. There is a need for close follow-up of patients surviving AKI to prevent progressive CKD and to reduce associated lethal cardiac events.