‘Early’ and ‘late’ timing for renal replacement therapy in acute kidney injury after cardiac surgery: a prospective, interventional, controlled, single-centre trial

OBJECTIVES Acute kidney injury after cardiac surgery (CS-AKI) is strongly associated with in-hospital mortality and morbidity. We aimed to investigate whether ‘early’ or ‘late’ initiation of renal replacement therapy (RRT) in patients with CS-AKI is associated with a survival benefit or more favourable outcomes. METHODS All patients who had undergone cardiac surgery at ‘Ospedali Riuniti’ of Ancona from July 2011 to February 2013 were prospectively enrolled and divided into two treatment groups: the ‘early’ approach was used during the first 10 months, and the ‘late’ approach during the next 10 months. ‘Early’ RRT was started after 6 h of urine output less than 0.5 ml/kg/h, whereas in the ‘late’ group, therapy started on the basis of persistent (>12 h) oliguria. A total of 1658 patients were enrolled in the trial. The primary outcome was operative mortality, and the secondary outcomes were length of intensive care unit and hospital stay. RESULTS The total number of patients treated with RRT was 59 (3.6%): 46 (5.5%) in the ‘early’ group and 13 (1.6%) in the ‘late’ group (P < 0.0001). Although RRT was significantly less utilized in the ‘late’ group, no significant difference in the primary and secondary outcomes was found, but a trend towards a better outcome in the ‘late’ group was observed. Furthermore, we found a significant difference in mortality between the two approaches in the subgroups of patients with preoperative renal dysfunction and in patients suffering from CS-AKI with a clear advantage of the late strategy. CONCLUSIONS Our results do not support the use of early RRT in CS-AKI. CLINICAL TRIAL REGISTRATION This trial is registered in the clinicaltrial.gov registry: NCT01961999.