**7. Outcomes in CRRT**

Outcomes of an increased dose of CRRT have been assessed in several randomized controlled trials and two meta-analyses (78-80,116-117). Conflicting results related to survival have been reported. To address the issue of optimal dose in CRRT and IHD, the United States VA/NIH Acute Renal Failure Trial Network study (ATN), the Randomized Evaluation of Normal versus Augmented Level of RRT study (RENAL) and two metaanalyses were performed. All studies found that, compared with standard intensity dialysis, higher intensity dialysis did not result in improved survival or clinical benefits:

In the United States VA/NIH Acute Renal Failure Trial Network study (ATN), all 1124 patients were treated with IHD, CRRT, or SLED based upon hemodynamic status. Patients were randomly assigned to one of two dosing arms:


The death rate at day 60 was the same for both groups (53.6 percent with intensive therapy and 51.5 percent with less intensive therapy). In addition, the duration of renal replacement therapy and the rate of recovery of kidney function or nonrenal organ failure were similar for both treatment arms. The group that received intensive therapy had an increased number of hypotensive episodes. Thus, more intensive renal support beyond that obtained with a standard thrice-weekly regimen (with a target Kt/V of 1.2 to 1.4 per treatment) or standard CRRT (with an effluent flow rate of 20 mL/kg per hour) does not improve clinical outcomes.

In the RENAL study (a trial in Australia and New Zealand), 1508 patients with AKI were randomly assigned to CVVHDF at an effluent flow of either 25 or 40 mL/kg per hour (119). At 90 days, mortality was the same in each group (44.7 percent, odds ratio 1.00, 95% CI 0.31 to 1.23). In addition, the incidence of patients who continued to receive renal replacement therapy at 90 days was similar with both dialysis doses (6.8 and 4.4 percent of higher and lower-intensity groups, odds ratio 1.59, 95% CI 0.86 to 2.92).

Two meta-analyses, one consisting of 3841 patients and 8 trials and the other 3999 patients and 12 trials, found that more intense therapy did not improve survival compared with less intensive regimens (118-119). There was significant trial heterogeneity.
