Ann Arbor, MI—Whether to use IV iodinated contrast media in patients with reduced kidney function has been an ongoing controversy. Now, the American College of Radiology and National Kidney Foundation have weighed in with a strong consensus statement.

In effect, the groups suggest that the risk of using the contrast media in patients with reduced kidney function has been overstated, according to information published in Radiology.

IV iodinated contrast media are commonly used with computed tomography (CT) to evaluate disease and to determine treatment response, but the associations point out that iodinated contrast media have been denied or delayed in patients with reduced kidney function due to perceived risks of contrast-induced acute kidney injury. Patients benefit from contrast media use, according to the statements; the practice of avoiding it can make it more difficult to get timely and accurate diagnoses in those patients.

“The historical fears of kidney injury from contrast-enhanced CT have led to unmeasured harms related to diagnostic error and diagnostic delay,” explained lead author Matthew S. Davenport, MD, associate professor of radiology and urology at the University of Michigan in Ann Arbor, Michigan. “Modern data clarify that this perceived risk has been overstated. Our intent is to provide multi-disciplinary guidance regarding the true risk to patients and how to apply a consideration of that risk to modern clinical practice.”

The report explained that, in clinical practice, a range of factors is used to determine whether IV contrast media should be administered. Among those are:
• Probability of an accurate diagnosis
• Alternative methods of diagnosis
• Risks of misdiagnosis
• Expectations about kidney function recovery
• Risk of allergic reaction

The authors emphasize that decisions are rarely based on a single consideration, such as risk of an adverse event specifically related to kidney impairment, and urge that the entire clinical scenario be taken into consideration.

The report also details key differences between contrast-induced acute kidney injury (CI-AKI) and contrast-associated acute kidney injury (CA-AKI). In CI-AKI, a causal relationship exists between contrast media and kidney injury, but, in CA-AKI, a direct causal relationship has not been demonstrated. The authors argue that past research has not appropriately distinguished between the two, leading to overstated risk.

“A primary explanation for the exaggerated perceived nephrotoxic risk of contrast-enhanced CT is nomenclature,” Dr. Davenport noted. “‘Contrast-induced’ acute kidney injury implies a causal relationship. However, in many circumstances, the diagnosis of CI-AKI in clinical care and in research is made in a way that prevents causal attribution. Disentangling contrast-induced AKI (causal AKI) from contrast-associated AKI (correlated AKI) is a critical step forward in improving understanding of the true risk to patients.”

The authors recommend IV normal saline for patients without contraindications, such as heart failure, who have acute kidney injury or an estimated glomerular filtration rate (eGFR) less than 30 mL/min per 1.73 m2 who are not undergoing maintenance dialysis.

As for individual and unusual high-risk circumstances, such as patients with multiple comorbid risk factors, they suggest that prophylaxis might be considered in patients with an eGFR of 30-44 mL/min per 1.73 m2 at the discretion of the ordering clinician.

In addition, the authors write that the presence of a solitary kidney should not independently influence decision-making regarding the risk of CI-AKI. They also advise that reducing the contrast media dose below a known diagnostic threshold should be avoided because that could also reduce diagnostic accuracy.

The statements advise that, when possible, medications that are toxic to the kidneys should be withheld by the referring clinician in patients at high risk, but that renal replacement therapy should not be initiated or altered only because contrast media was administered.

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