Acute kidney injury is a common complication of acute illness, affecting approximately 2 to 7% of hospitalized patients and more than 35% of critically ill patients. While renal-replacement therapy is the main treatment method for patients with acute kidney injury, the optimal timing for the initiation, method, and dosing of therapy is uncertain. Given this uncertainty, the Acute Renal Failure Trial Network (ATN) study was established to determine whether more intensive renal replacement therapy decreases mortality among critically ill patients with acute kidney injury.

The study was a multicenter, prospective, randomized trial of two strategies for renal-replacement therapy in patients with acute kidney injury. Participants were randomized to receive intensive (i.e., intermittent hemodialysis and sustained low-efficiency dialysis six times per week and continuous venovenous hemodiafiltration at 35 ml/kg of body weight/hour) or less intensive renal-replacement therapy (i.e., the corresponding treatments were provided three times per week and at 20 ml/kg/hour). The assigned renal-replacement therapy was provided for up to 28 days after randomization or until recovery of kidney function, discharge from acute care, withdrawal of life-sustaining therapy, or death. The primary outcome measure was death from any cause by day 60. Recovery of kidney function (defined as lack of need for continuing dialysis support, with a minimum creatinine clearance of 20 ml/minute), duration of renal-replacement therapy, lengths of stay in the intensive care unit (ICU) and hospital, and days free of nonrenal organ failure were also assessed.

Results showed that the primary outcome measure, death from any cause by day 60, did not differ between the two groups. Additionally, recovery of renal function and reduction in the rate of nonrenal organ showed no improvement with intensive renal support. The study found no added benefit from an intensive (high-dose) treatment strategy as compared with the more conventional, less-intensive treatment strategy.

The study investigated whether more intensive renal-replacement therapy decreases mortality among critically ill patients with acute kidney injury.

The primary outcome measure was death from any cause by day 60. Secondary outcome measures included in-hospital death, recovery of kidney function (defined as lack of need for continuing dialysis support, with a minimum creatinine clearance of 20 ml/minute), the duration of renal-replacement therapy, lengths of stay in the intensive care unit (ICU) and hospital, days free of nonrenal organ failure (defined as days on which individual Sequential Organ Failure Assessment (SOFA) organ system scores were 0 to 2), and whether the patients returned to their previous living situation and did not require dialysis by day 60.

Patients ages 18 years or older who met the following criteria were eligible for enrollment:

• Acute kidney injury clinically consistent with acute tubular necrosis
• Plan for renal-replacement therapy
• Failure of one or more nonrenal organ systems, defined as a nonrenal SOFA organ system score ≥ 2 (range, 0 to 4, with a higher score indicating more severe organ dysfunction), or sepsis

Patients were excluded if they had undergone more than one session of intermittent hemodialysis or sustained low-efficiency dialysis or had received more than 24 hours of continuous renal-replacement therapy prior to enrollment. Detailed exclusion criteria are documented in the study protocol.

Results showed that the primary outcome measure, death from any cause by day 60, did not differ between the two groups. Intensive renal support in critically ill patients with acute kidney injury did not improve recovery of renal function or reduce the rate of nonrenal organ failure as compared with less-intensive therapy. The study found no added benefit from an intensive (high-dose) treatment strategy as compared with the more conventional, less-intensive treatment strategy.