Used with CRRT, it lowered patient mortality.


A renal tubule assist device (RAD) may help improve survival of patients with acute kidney injury (AKI), new data show.

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The findings come from a phase II multicenter trial involving 58 people. Those who used the device in addition to continuous renal replacement therapy (CRRT) had a 28-day mortality rate of 33%. By comparison, the rate was 61% for patients receiving CRRT alone. The RAD group had a 52% reduced risk of death compared with those not treated with the device, after adjusting for cause of disease.


CRRT removes uremic toxins and corrects fluid, electrolyte and acid-base balance in people with AKI. The RAD performs certain metabolic, endocrine, and immunologic functions of the kidneys that CRRT cannot.


The RAD forms a sort of ‘living membrane,’ thus helping create a favorable environment for repair of kidney tubule cells and hence the overall prognosis of AKI patients. A team led by David Humes, MD, professor of internal medicine at the University of Michigan in Ann Arbor, has been developing and testing a RAD for more than 10 years.


In this multicenter, open-label study published in the Journal of the American Society of Nephrology (2008, published online ahead of print), Dr. Humes and his 12 co-investigators randomized 40 consecutive patients with acute renal failure to CRRT plus RAD, and another 18 to CRRT alone. Twenty-one (52.5%) of the RAD group patients finished the study, as did four (22.2%) of the CRRT-alone patients. The two groups were similar, and the team analyzed the results on an intention-to-treat basis.


Malfunction of the RAD cartridge was reported in one patient, and another patient randomized to RAD died before the device could be hooked up. In a third individual, the RAD was incorrectly inserted into the blood circuit. One RAD was disconnected prematurely because of leakage in one of the tubing connectors. Treatment of 14 other RAD patients was stopped early because of clotting; the investigators reported that in the majority of these cases, the clots originated within the CRRT cartridge. They did not report the rate of clotting in the CRRT-alone group.


By day 28, one RAD patient had dropped out of the study and 13 (33%) of the 39 RAD patients had died. Eleven (61%) of the CRRT-alone patients had died after 28 days, and the absolute reduction of mortality in the RAD group versus the CRRT-alone group was maintained at days 90 and 180. A Kaplan-Meier survival curve indicated that, out to 180 days, survival was significantly higher in the RAD patients.


“The results of this study suggest that CRRT plus RAD may have a favorable impact on patient survival,” commented another specialist in the field, Mark Okusa, MD, the John C. Buchanan Distinguished Professor of Medicine at the University of Virginia Health System in harlottesville.


“These results are consistent with the team’s previous animal studies and a Phase I/II human trial using renal tubule cells and CRRT. However, before we can say that CRRT and RAD is effective clinically in reducing mortality in patients with AKI, confirmation in a larger, multicenter study is important.”


“If the results of this study are confirmed, this device would represent a major advancement for the treatment of AKI,” Dr. Okusa added. “The use of cell-based therapy with current dialytic methods holds great promise for the not-too-distant future.”