RESUMO
OBJECTIVES: Oliguria after cardiac surgery remains of uncertain clinical significance. Therefore, we investigated the relationship of acute kidney injury severity across urine output and creatinine domains with the risk for major adverse kidney events at 180 days. We aimed to determine the impact of acute kidney injury after cardiac surgery. METHODS: In a retrospective multicenter study, we investigated the relationship of acute kidney injury severity across urine output and creatinine categories with the risk for major adverse kidney events at 180 days-the composite of death, dialysis, and persistent renal dysfunction-using a large database of patients undergoing cardiac surgery at 1 of 5 hospitals within the regional medical system. We analyzed electronic records from 6637 patients treated between 2008 and 2014, of whom 5389 (81.2%) developed any acute kidney injury within 72 hours of surgery. We stratified patients by levels of urine output or serum creatinine according to Kidney Disease Improving Global Outcomes criteria for acute kidney injury. RESULTS: Major adverse kidney events at 180 days increased from 4.5% for no acute kidney injury to 61.3% for stage 3 acute kidney injury (P < .001). Death or dialysis by day 180 was 2.4% for those with no acute kidney injury and 46.7% for those with acute kidney injury stage 3 (P < .001). Isolated oliguria was common (42.6%), and isolated azotemia was rare (6.1%). Even stage 1 acute kidney injury by oliguria alone was associated with an increased risk of major adverse kidney events at 180 days (odds ratio, 1.76; 1.20-2.57; P = .004), mainly driven by persistent renal dysfunction (odds ratio, 2.01; 1.26-3.18; P = .003). CONCLUSIONS: Acute kidney injury is common in patients undergoing cardiac surgery, and even milder forms of acute kidney injury, including isolated stage 1 oliguria, are associated with adverse long-term consequences.