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J Am Heart Assoc. 2018 Mar 13;7(6). pii: e008181. doi: 10.1161/JAHA.117.008181.

Preoperative Short-Term Calorie Restriction for Prevention of Acute Kidney Injury After Cardiac Surgery: A Randomized, Controlled, Open-Label, Pilot Trial.

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Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Germany.
Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Germany.
Department of Cardiothoracic Surgery, University of Cologne, Germany.
Center for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Germany.
Institute of Medical Statistics and Computational Biology, University of Cologne, Germany.
Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Germany



Acute kidney injury is a frequent complication after cardiac surgery and is associated with adverse outcomes. Although short-term calorie restriction (CR) has proven protective in rodent models of acute kidney injury, similar effects have not yet been demonstrated in humans.


CR_KCH (Effect of a Preoperative Calorie Restriction on Renal Function After Cardiac Surgery) is a randomized controlled trial in patients scheduled for cardiac surgery. Patients were randomly assigned to receive either a formula diet containing 60% of the daily energy requirement (CR group) or ad libitum food (control group) for 7 days before surgery. In total, 82 patients were enrolled between April 16, 2012, and February 5, 2015. There was no between-group difference in the primary end point of median serum creatinine increment after 24 hours (control group: 0.0 mg/dL [-0.1 - (+0.2) mg/dL]; CR group: 0.0 mg/dL [-0.2 - (+0.2) mg/dL]; P=0.39). CR prevented a rise in median creatinine at 48 hours (control group: +0.1 mg/dL [0.0 - 0.3 mg/dL]; CR group: -0.1 mg/dL [-0.2 - (+0.1) mg/dL]; P=0.03), with most pronounced effects observed in male patients and patients with a body mass index >25. This benefit persisted until discharge: Median creatinine decreased by 0.1 mg/dL (-0.2 - 0.0 mg/dL) in the CR group, whereas it increased by 0.1 mg/dL (0.0 - 0.3 mg/dL; P=0.0006) in the control group. Incidence of acute kidney injury was reduced by 5.8% (41.7% in the CR group compared with 47.5% in the control group). Safety-related events did not differ between groups.


Despite disappointing results with respect to creatinine rise within the first 24 hours, the benefits observed at later time points and the subgroup analyses suggest the protective potential of short-term CR in patients at risk for acute kidney injury, warranting further investigation.


URL: Unique identifier: NCT01534364.


acute kidney injury; calorie restriction; cardiac surgery; dietary restriction; preconditioning

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