Background: Acute renal failure (ARF) in the critically ill is associated with extremely high mortality rates. Understanding the changing spectrum of ARF will be necessary to facilitate quality improvement efforts and to design successful interventional trials.
Methods: We conducted an observational cohort study of 618 patients with ARF in intensive care units at five academic medical centers in the United States. Participants were required to sign (or have a proxy sign) informed consent for data collection. A comprehensive data collection instrument captured more than 800 variables, most on a daily basis, throughout the course of ARF. Patient characteristics, dialysis status, and major outcomes were determined and stratified by clinical site.
Results: The mean age was 59.5 years, 41% were women, and 20% were of minority race or ethnicity. There was extensive comorbidity; 30% had chronic kidney disease, 37% had coronary artery disease, 29% had diabetes mellitus, and 21% had chronic liver disease. Acute renal failure was accompanied by extrarenal organ system failure in most patients, even those who did not require dialysis. Three hundred and ninety-eight (64%) patients required dialysis. The in-hospital mortality rate was 37%, and the rate of mortality or nonrecovery of renal function was 50%. The median hospital length of stay was 25 days (26 days, excluding patients who died).
Conclusion: There is a changing spectrum of ARF in the critically ill, characterized by a large burden of comorbid disease and extensive extrarenal complications, obligating the need for dialysis in the majority of patients. There is wide variation across institutions in patient characteristics and practice patterns. These differences highlight the need for additional multicenter observational and interventional studies in ARF.