Five-year outcomes of severe acute kidney injury requiring renal replacement therapy

Background. Current research priorities in critical care medicine are focusing on long-term outcomes of survivors of critical illness. Severe acute kidney injury (AKI) is a common occurrence in intensive care. However, few studies have followed up these patients beyond 12 months after hospital discharge. Methods. Of a cohort of 425 patients, 226 survivors with severe AKI necessitating renal replacement therapy (RRT) were followed up for 60 months after hospital discharge. None of these patients had pre-existing kidney disease. Vital status and renal function were documented annually for 5 years. Results. None of the discharged or transferred patients was dependent on RRT; 57% had complete recovery and 43% had partial recovery of renal function. During the first year after hospital discharge, 18% of survivors died, during the second year 4% and during the third to fifth year 2% per year. At 5 years, 25% of the cohort were still alive. Further improvement in renal function (eGFR) was noted in 26 patients within the first year only. Deterioration of renal function occurred in eight patients. At 5 years, renal function was normal in 86% of the remaining survivors, it was impaired in 9% and 5% of the patients alive needed dialysis again. The proportional Cox regression analysis model showed that pre-existing extrarenal comorbidity, surgery and partial recovery of renal function were independent determinants of long-term survival. Conclusions. This prospective observational study indicates that severe AKI is not only a determinant of excess in-hospital case fatalities of critically ill patients, but it also carries significant implications for long-term mortality.