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Creatinine clearance helps set safe dose of contrast medium

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Among patients undergoing cardiac procedures, a lower dose of contrast medium based on calculated creatinine clearance may reduce the risk of contrast-induced nephropathy, investigators report in the Journal of the American College of Cardiology for August 23.

“Our study supports the need for minimizing contrast dose in patients with renal dysfunction,” the authors comment.

They note that the safe level of contrast used during PCI remains unclear, even though the need to minimize the dose is generally acknowledged. Dr. Hitinder S. Gurm, at the University of Michigan Cardiovascular Center in Ann Arbor, and colleagues hypothesized that a dose estimation based on calculated creatinine clearance (CCC) might be a simple way to define a safe dose.

To investigate, the team analyzed data from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium registry on 58,957 patients undergoing PCI. The CCC was calculated with the Cockcroft-Gault equation, which has been conventionally used for renal dosing of medications.

The dose of contrast administered ranged from 5 to 900 mL, according to the report. Contrast-induced nephropathy, defined as impairment in renal function resulting in an absolute increase in serum creatinine of at least 0.5 mg/dL from baseline, occurred in 1,470 patients, and 142 patients required dialysis.

The investigators found that when the ratio of contrast dose-to-CCC exceeded 2, the risk of contrast-induced nephropathy approached statistical significance (adjusted odds ratio, 1.16), as did the risk of requiring dialysis (adjusted OR, 1.72).

When the contrast-to-CCC ratio was 3 or higher, the respective risks were “dramatically elevated” (adjusted odds ratio 1.46 and 1.89), Dr. Gurm and colleagues calculated.

Given these results, they conclude, “A planned contrast volume restricted to less than thrice and preferably twice the CCC might be valuable in reducing the risk of contrast-induced nephropathy and nephropathy requiring dialysis.”

Renal Function-Based Contrast Dosing to Define Safe Limits of Radiographic Contrast Media in Patients Undergoing Percutaneous Coronary Interventions
J Am Coll Cardiol 2011;58:907-914.