Acute renal failure definitions and classification: Time for change?

ARF continues to be a vexing problem occupying a significant amount of time for clinicians and offering numerous challenges to investigators. Despite the recognition that ARF contributes to adverse outcomes in the critically ill, little progress has been made in managing this condition. One of the key impediments to progress is the lack of a uniform definition for this disease. Current definitions that rely on changes in serum creatinine and urine output are neither sensitive nor specific. We propose a new classification for ARF that incorporates information from other domains in an effort to enhance descriptive data and, we hope, improve decision making. Future studies will need to validate the "multidimensional diagnosis of ARF" construct and to improve the content and precision of components within each domain. What we present here (or a variation thereof) is not definitive, just a necessary first step. On the frontier, we see much more precision in ARF definitions, effective interventions, and, ultimately, mortality rates in the single digits.