Timing of Renal Replacement Therapy in Acute Kidney Injury

Renal replacement therapy (RRT) is commonly and increasingly utilized in critically ill patients with severe acute kidney injury (AKI). The issue of when to start RRT in a critically ill patient with AKI has long troubled clinicians.

Currently, there is a paucity of high-quality evidence to guide clinician decision-making on the optimal time to start RRT. This lack of evidence has translated into wide variation in treatment patterns and practices. In patients developing life-threatening complications of AKI, the decision to start RRT is largely indisputable; however, in the absence of such complications, the optimal thresholds to start RRT that translates into improved outcomes for patients are unknown. Available evidence from observational studies and clinical trials have considerable limitations for translation to clinical practice due to their retrospective, post hoc secondary design, their small sample sizes, heterogeneity in study populations and illness severity, variation in the definitions of AKI and in the timing of or thresholds for starting RRT and the risk of residual confounding and bias related to the association between the timing of RRT and outcome.

Several large randomized trials are planned or ongoing, and the results of these trials will greatly inform best clinical practice and will help reduce unnecessary variation in the practice of RRT prescription. For now, the decision on the appropriate time to start RRT is naturally complex, integrating numerous variables, and should largely be individualized.