Changes in the incidence and outcome for early acute kidney injury in a cohort of Australian intensive care units

Background: There is limited information on whether the incidence of acute kidney injury ( AKI) in critically ill patients has changed over time and controversy on whether its outcome has improved. Methods: We interrogated the Australian New Zealand Intensive Care Society ( ANZICS) Adult Patient Database ( APD) to obtain data on all adult admissions to 20 Australian intensive care units ( ICUs) for >= 24 hours from January 1(st) 1996 to December 31(st) 2005. Trends in incidence and mortality for ICU admissions associated with early AKI were assessed. Results: There were 91,254 patient admissions to the 20 study ICUs, with 4,754 cases of AKI for an estimated crude cumulative incidence of 5.2% ( 95% CI 5.1-5.4). The incidence of AKI increased during the study period with an estimated annual increment of 2.8% ( 95% CI 1.0-5.6, p=0.04). Crude hospital mortality was significantly higher for patients with AKI ( 42.7% vs. 13.4%, odds ratio ( OR): 4.8, 95% CI 4.5-5.1, p<0.0001). However, there was also a decrease in AKI crude mortality ( annual percent change -3.4%, 95% CI -4.7 to -2.12, p<0.001), which was not seen in patients without AKI. After co-variate adjustment, AKI remained associated with a higher mortality ( OR; 1.23, 95% CI, 1.14-1.32, p<0.001) and there was a declining trend in its OR for hospital mortality. Conclusions: Over the last decade, in a large cohort of critically ill patients admitted to 20 Australian ICUs, there has been a significant rise in the incidence of early AKI while the mortality associated with it has declined.