Preexisting Chronic Kidney Disease: A Potential for Improved Outcomes from Acute Kidney Injury

Background and objectives: Acute kidney injury (AKI) is associated with adverse outcomes in critically ill patients. The influence of preexisting chronic kidney disease (CKD) on AKI outcomes is unclear. Design, setting, participants, & measurements: We analyzed data from a prospective observational cohort study of AKI in critically ill patients who received nephrology consultation: the Program to Improve Care in Acute Renal Disease. In-hospital mortality rate, length of stay, and dialysis dependence were compared in patients with and without a prior history of CKD, defined by an elevated serum creatinine, proteinuria, and/or abnormal renal ultrasound within a year before hospitalization. We hypothesized that patients with AKI and prior history of CKD would have lower mortality rates, shorter lengths of stay, and higher rates of dialysis dependence than patients without prior history of CKD. Results: Patients with AKI and a prior history of CKD were older and underwent nephrology consultation earlier in the course of AKI. In-hospital mortality rate was lower (31 versus 40%, P = 0.04), and median intensive care unit length of stay was 4.6 d shorter (14.7 versus 19.3 d, P = 0.001) in patients with a prior history of CKD. Among dialyzed survivors, patients with prior CKD were also more likely to be dialysis dependent at hospital discharge. Differences in outcome were most evident in patients with lower severity of illness. Conclusions: Among critically ill patients with AKI, those with prior CKD experience a lower mortality rate but are more likely to be dialysis dependent at hospital discharge. Future studies should determine optimal strategies for managing AKI with and without a prior history of CKD. Clin J Am Soc Nephrol 4. 1914-1919, 2009. doi 10 2215/CJN 01690309