Poor Long-Term Survival After ICU Acute Kidney Injury

By Will Boggs MD

March 24, 2014

NEW YORK (Reuters Health) - Long-term survival remains poor after acute kidney injury (AKI) in the intensive care unit, but most of those who do survive don't need maintenance dialysis, according to long-term follow-up results from the randomized RENAL trial.

"We were surprised by the long-term mortality rate, in part because there is very little prospective data and it is hard to translate the existing retrospective analyses to a clinical population," Dr. Martin Gallagher from The George Institute for Global Health and University of Sydney, Sydney, Australia told Reuters Health. "In addition, the focus of much of the literature (certainly in nephrology) in recent years has highlighted the risk of these patients ending up on dialysis, so the mortality rate relative to the dialysis rates was very surprising."

In a previous analysis, Dr. Gallagher and colleagues found no difference in all-cause mortality between ICU patients with AKI in the RENAL study who were randomized to receive higher or lower intensities of continuous dialysis. This newer report presents longer-term outcomes in 350 patients from the same trial.

The overall mortality rate was 62% after a median of 42.4 months post-randomization, and the median survival did not differ between the higher- and lower-intensity RRT groups (8.1 vs 8.9 months; p=0.49).

Only 44 patients (5.4% of those alive at day 90) required maintenance dialysis (5.1% of the lower intensity group; 5.8% of the higher intensity group; p=0.69), the authors reported online February 11th in PLoS Medicine.

At follow-up, mean estimated glomerular filtration rate (eGFR) remained low, at 58 mL/min/1.73 m sq, and 42.1% of patients had micro- or macro-albuminuria.

Quality of life scores did not differ between the higher and lower intensity RRT groups.

Multivariate predictors of long-term mortality included increasing age, worse APACHE III score, and higher serum creatinine at randomization. On the other hand, study treatment intensity did not influence mortality.

"In the end, this is a very sick patient population (around 44% mortality at 90 days) so the factors driving that high early mortality are likely still at play in the longer term," Dr. Gallagher said.

"The survivors of an episode of severe AKI (i.e., requiring dialysis) remain at an elevated risk for mortality and proteinuria well beyond the time of hospital discharge, so assessment and management of risk factors is likely to be valuable," Dr. Gallagher said.

"Our other work has looked at a number of possible factors that might be contributing to the early mortality (within 90 days), such as fluid resuscitation, dialysis modality, and timing of dialysis initiation but, as yet, we don't have any proven therapies," Dr. Gallagher said. "I suspect understanding the long term mortality drivers will be harder as the event rates are lower and any interventions will need to be delivered over a longer time frame."

"An important finding was the high rates of proteinuria in survivors, which is a powerful risk factor for cardiovascular disease and for which treatments such as (angiotensin converting enzyme inhibitors and angiotensin receptor blockers) have shown benefit in other populations (e.g., diabetic renal disease)," Dr. Gallagher added. "If that finding were replicated in other populations, then there may be value in examining their role in this patient population."

"This paper shows us that high intensity alone is not the best option," Dr. Sejoong Kim from the Seoul National University College of Medicine in South Korea told Reuters Health. "That means we should focus on other unsolved things."

"Nevertheless, dialysis dependency in survivors was lower than I expected," Dr. Kim concluded. "Still, the high prevalence of proteinuria suggests that nephrologists should take care of those survivors."

SOURCE: http://bit.ly/1laH0v9

PLoS Medicine 2014.

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