Developing a consensus classification system for acute renal failure.

A biochemical definition and classification system for acute renal dysfunction is long overdue. Its absence has impeded progress in clinical and even basic research concerning a syndrome associated with mortality rates of 30 to 80%. No definition of acute renal dysfunction will be perfect, but the absence of a definition or, worse, more than 35 separate definitions, as found in the literature, is unacceptable. Many of the challenges, considerations, and controversies associated with achieving consensus and developing a classification for acute renal dysfunction are addressed. Recommendations for validating a classification system are also considered.