Relationship between duration of hospital-acquired acute kidney injury and mortality: a prospective observational study

BACKGROUND/AIMS New definitions of acute kidney injury (AKI) have recently emerged. Some studies have suggested that duration of AKI is an additional predictive parameter for mortality. Here, we evaluated whether AKI duration was predictive of long-term mortality in patients with hospital-acquired acute kidney injury (HAAKI). METHODS We prospectively enrolled patients who developed HAAKI at an urban university hospital, from September 2007 to August 2008 and followed them until December 2011. Patients were divided into two groups by duration of the AKI (1 to 5 days vs. ≥ 6 days), and long-term mortality was compared. RESULTS HAAKI developed in 1.2% of patients during the enrollment period. The median follow-up period was 240 days (interquartile range, 53 to 1,428). In 42.3% of patients (n = 52), the AKI lasted 1 to 5 days, while it lasted ≥ 6 days in 57.7% (n = 71). Survival analysis showed that a longer duration of AKI increased the risk of death. Long-term survival was significantly different in the two groups. CONCLUSIONS The duration of AKI influenced mortality rates in hospitalized patients. Thus, AKI duration is a parameter affecting mortality in HAAKI.