Contrast-Induced Nephropathy Is 'Overstated,' Say Groups

Nancy A. Melville

January 21, 2020

The risk of acute kidney injury (AKI) with the use of modern intravenous contrast media in CT imaging among people with reduced renal function has been exaggerated to the detriment of those in need of diagnostic imaging, according to joint consensus statements and recommendations from the American College of Radiology and US National Kidney Foundation.

"The historical fears of kidney injury from contrast-enhanced CT have led to unmeasured harms related to diagnostic error and diagnostic delay," lead author of the statement Matthew S. Davenport, MD, said in a press statement issued by the Radiological Society of North America.

"Modern data clarify that this perceived risk has been overstated," added Davenport, an associate professor of radiology and urology at the University of Michigan in Ann Arbor.

"Our intent is to provide multidisciplinary guidance regarding the true risk to patients and how to apply a consideration of that risk to modern clinical practice," write Davenport and colleagues in the statement, simultaneously published January 21 in Radiology and Kidney Medicine.

Recommendations for Intravenous Contrast Media Use

Patients with reduced kidney function have commonly been denied or had delayed CT imaging because of concerns of iodinated contrast-induced AKI, with such delays said to potentially lead to delayed diagnosis or even misdiagnoses.

Evidence of the risks, however, is clouded by several factors, primarily because of the historic lack of control groups sufficient to separate contrast-induced AKI (ie, AKI caused by contrast media administration) from contrast-associated AKI (AKI coincident with contrast media administration), say Davenport and colleagues.

"Although the true risk of contrast-induced AKI remains uncertain for patients with severe kidney disease, prophylaxis with intravenous normal saline is indicated for patients who have AKI or an estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73m2 who are not undergoing maintenance dialysis," provided patients have no contraindication to the prophylaxis, such as heart failure, the authors state.

"In individual high-risk circumstances, prophylaxis may be considered in patients with an eGFR of 30-44 mL/min/1.73m2 at the discretion of the ordering clinician," they add.

They also note that the presence of a solitary kidney should not independently influence decision-making regarding the risk of contrast-induced AKI.

"In patients with a single normal or partially functioning kidney, clinical risk should be determined based on overall kidney function (ie, eGFR) and clinical circumstances (ie, AKI)," the authors write.

Additionally, they note, the ad hoc reduction of contrast media dose below a known diagnostic threshold should be avoided because of the risk of lowering the diagnostic accuracy of the CT imaging.

And if possible, referring clinicians should withhold nephrotoxic medications in patients at high risk.

"However, renal replacement therapy should not be initiated or altered solely based on contrast media administration," they advise.

Take Into Account Other Considerations, Look at Entire Clinical Scenario

Importantly, the recommendations apply specifically to intravenous contrast media administration, as opposed to intra-arterial use, such as coronary artery angiography, which has unique considerations, including a requirement for arterial access, and potential atheroembolic complications, the authors note.

Furthermore, it is important to underscore that a multitude of additional considerations can factor into decisions to use intravenous contrast media, ranging from the probability of an accurate diagnosis and alternative diagnostic methods to expectations of kidney function recovery.

Therefore, "these statements should be considered in the context of the entire clinical scenario," the authors indicate.

Differentiating Contrast-Induced From Contrast-Associated AKI "Critical"

Davenport also emphasized that more work is needed to better define and distinguish the true causal factors of contrast-induced AKI.

"A primary explanation for the exaggerated perceived nephrotoxic risk of contrast-enhanced CT is nomenclature," said Davenport.

"'Contrast-induced' AKI implies a causal relationship. However, in many circumstances, the diagnosis of contrast-induced AKI in clinical care and in research is made in a way that prevents causal attribution," he explained in the press statement.

"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," he added.

And in the statement, Davenport and colleagues point out that additional prospective controlled data "are needed in adult and pediatric populations to clarify the risk of contrast-induced AKI."

Debate Continues

The issues of contrast-induced and contrast-associated AKI remain subjects of debate, as previously reported by Medscape Medical News.

That article notes that although a meta-analysis of more than 100,000 patients in controlled studies showed no significant associations between contrast-enhanced CT and kidney injury, other experts — such as the authors of an editorial — point to methodologic limitations of some studies and argue that the existence of contrast-associated AKI is not "a myth."

Davenport has reported no relevant financial relationships. Disclosures for the other authors are listed in the article.

Radiology. Published online January 21, 2020. Full text

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