Despite being a concern for years, new research has suggested that intravenous contrast material exposure does not increase the risk of acute kidney injury (AKI) in patients undergoing a CT scan.

Jennifer S. McDonald, PhD, of the Mayo Clinic in Rochester, Minn., and colleagues found that the true of incidence of contrast-induced nephropathy is substantially lower than previously estimated, and that baseline renal function has a greater impact on the incidence of AKI. Their findings were published in the April issue of Radiology.

“Contrast material–induced nephropathy cannot be differentiated from contrast material–independent causes of AKI, in a predominantly inpatient cohort, even in patients with severely compromised renal function,” wrote the authors.

McDonald and colleagues used estimated glomerular filtration rate (eGFR) to characterize baseline renal function in a patient population of more than 12,500 individuals who underwent CT between 2000 and 2010. They found that the incidence of AKI significantly increased with decreasing baseline eGFR.

However, when the patients were stratified by baseline eGFR and those who received contrast material were compared with those who didn’t, the authors found that the incidence of AKI did not differ significantly between the contrast and noncontrast groups in any of the eGFR subgroups.

“The current findings provide additional evidence that the incidence of intravenous contrast material–mediated AKI is obscured by comparable rates of contrast material–independent AKI and suggest that eGFR-based definitions of AKI risk are incapable of aiding identification of true contrast material–mediated AKI from contrast material–independent AKI,” wrote McDonald and colleagues.