An Assessment of AKIN Criteria for Hospital-Acquired Acute Kidney Injury: A Prospective Observational Cohort Study

BACKGROUND AND AIMS: The Acute Kidney Injury Network (AKIN) criteria assert a new definition for acute kidney injury (AKI). We investigated the incidence of hospital-acquired AKI, along with the clinical characteristics and outcomes in hospitalized patients according to AKIN stage. METHODS: We performed a prospective, observational, single-center study. We monitored serum creatinine everyday for all patients using a hospital data survey system during the study period from September 2007 to February 2008. RESULTS: Hospital-acquired AKI occurred in 1.2% of all hospitalized patients during the study period. Among patients with AKI, 29.2% were in stage 1, 36.5% were in stage 2 and 34.4% were in stage 3. A significantly higher rate of renal recovery was observed in patients with lower-stage injuries (71.4, 60.0, and 21.2% for stages 1, 2, and 3, respectively). Mortality for patients with stage 3 AKI (51.5%) was significantly higher than that for patients with stages 1 or 2 (p < 0.013). Independent risk factors for mortality in patients with AKI included malignancy, stage 3 AKI, diuretic use, and intensive care unit admission prior to AKI. CONCLUSIONS: Our findings support the utility of the AKIN criteria for hospital-acquired AKI, and demonstrate that stage 3 AKI poses a significant risk for poor patient and renal outcomes.