Short and long-term outcome of patients with severe acute kidney injury requiring renal replacement therapy

Background: Severe acute kidney injury (AKI) occurs in 2-7% of all hospital admissions and is an independent poor prognostic marker. Nevertheless, information on the long-term outcome of AKI and the factors influencing this is limited. Aim: To describe the short- and long-term outcome of patients requiring renal replacement therapy (RRT) for severe AKI and to examine factors affecting patient survival and renal recovery. Design and methods: Single centre retrospective analysis of 481 consecutive patients over a period of 39 months. Follow-up: 12 months. Primary and secondary outcomes: overall mortality and RRT dependency at 30 days, 90 days and 1 year. Results: Survival at 30 days, 90 days and 1 year was 54.4, 47.2 and 37.6%, respectively. RRT independency at 30 days, 90 days and 1 year was 35.2, 27.2 and 25.8%, respectively. Of those RRT independent at 90 days, 55% had ongoing chronic kidney disease. There were two distinct groups of patients: Group A (haemofiltration in ITU) and Group B (intermittent haemodialysis in the renal unit). Patient survival was worse in Group A while RRT independence was higher. Independent predictors of survival included renal cause of AKI and lower CI score in Group A and renal or post-renal cause of AKI, younger age and the absence of malignancy in Group B. Independent predictors of renal recovery included the presence of sepsis in Group A and pre- or post-renal cause of AKI in Group B. Conclusions: The short- and long-term survival outcome of severe AKI requiring RRT remains poor. Among those who survive, a significant number either continue to require RRT or have residual renal impairment necessitating ongoing follow-up.