Incidence, risk factors and 90-day mortality of patients with acute kidney injury in Finnish intensive care units: the FINNAKI study

We aimed to determine the incidence, risk factors and outcome of acute kidney injury (AKI) in Finnish ICUs. This prospective, observational, multi-centre study comprised adult emergency admissions and elective patients whose stay exceeded 24 h during a 5-month period in 17 Finnish ICUs. We defined AKI first by the Acute Kidney Injury Network (AKIN) criteria supplemented with a baseline creatinine and second with the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. We screened the patients' AKI status and risk factors for up to 5 days. We included 2,901 patients. The incidence (95 % confidence interval) of AKI was 39.3 % (37.5-41.1 %). The incidence was 17.2 % (15.8-18.6 %) for stage 1, 8.0 % (7.0-9.0 %) for stage 2 and 14.1 % (12.8-15.4 %) for stage 3 AKI. Of the 2,901 patients 296 [10.2 % (9.1-11.3 %)] received renal replacement therapy. We received an identical classification with the new KDIGO criteria. The population-based incidence (95 % CI) of ICU-treated AKI was 746 (717-774) per million population per year (reference population: 3,671,143, i.e. 85 % of the Finnish adult population). In logistic regression, pre-ICU hypovolaemia, diuretics, colloids and chronic kidney disease were independent risk factors for AKI. Hospital mortality (95 % CI) for AKI patients was 25.6 % (23.0-28.2 %) and the 90-day mortality for AKI patients was 33.7 % (30.9-36.5 %). All AKIN stages were independently associated with 90-day mortality. The incidence of AKI in the critically ill in Finland was comparable to previous large multi-centre ICU studies. Hospital mortality (26 %) in AKI patients appeared comparable to or lower than in other studies.