The increased long-term risk of death for intensive-care patients with acute kidney injury (AKI) who are treated with renal replacement therapy (RRT) was highlighted in a recent follow-up of participants from the Randomised Evaluation of Normal vs Augmented Levels of RRT (RENAL) randomized controlled trial.

Martin Gallagher, MBBS, MPH, Senior Director of the Renal and Metabolic Division at the George Institute for Global Health in Sydney, Australia, and colleagues prospectively examined the long-term outcomes and effects of RRT dosing in intensive care unit (ICU) patients with AKI, extending the follow-up of 1,464 RENAL participants (97%) from 90 days to four years after randomization. The subjects, all aged 18 years or older, had been randomized to receive 25 mL/kg/h (lower intensity) or 40 mL/kg/h (higher intensity) of continuous hemodiafiltration.

At a median 43.9 months’ post-randomization, 468 of the 743 lower-intensity patients (63%) and 444 of the 721 higher-intensity patients (62%) had died. However, only 21 of the 411 survivors to day 90 (5.1%) in the lower-intensity group and only 23 of the 399 survivors to day 90 (5.8%) in the higher-intensity group required maintenance dialysis.  

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Albuminuria was common in both groups, afflicting 40% of the lower-intensity survivors and 44% of the higher-intensity survivors. Quality of life did not differ between the two treatment groups.

“Only one third of randomized patients [with AKI] were alive 3.5 years [after undergoing RRT in the ICU], a lower survival than seen in [recognized] high-mortality conditions such as the acute respiratory distress syndrome,” Dr. Gallagher and his co-investigators pointed out in PLoS Medicine (2014;11[2]:e1001601). “Although in our patients the risk of subsequent maintenance dialysis dependence is low, almost half have evidence of significant proteinuria, portending further risk in years to come. These findings support the view that survivors of AKI are at increased risk and that closer surveillance may be justified.”

The authors also noted that in their cohort randomized to differing doses of continuous RRT, the increased risk of death continued well beyond hospital discharge and was not altered by receiving more intense dialysis treatment.