Study: CT contrast poses minimal risks to patients with mild kidney impairment

Patients with mild to moderate renal dysfunction are at low risk for nephropathy resulting from the administration of CT contrast agents, according to results of a study published in the June issue of the American Journal of Roentgenology.

Contrast agents have generally been associated with complications resulting in injuries to patients who suffer from kidney impairment, according to Michael Garfinkle, MD, and his colleagues at the University of Saskatchewan in Saskatoon, Canada. “Many previous studies analyzing the incidence of CT contrast agent–induced nephropathy have assumed that all acute kidney injuries occurring after imaging are attributable to contrast agent administration,” wrote Garfinkle and colleagues. “However, acute kidney injury is common even among hospitalized patients who have not received contrast agent.”

Garfinkle and his team set out to test a new method of estimating the renal impairment risks associated with CT contrast agents. To do so they assessed the incidence of acute kidney injury and dialysis after acute kidney injury 24–48 hours after the initial exam, as well as in a delayed period 72–96 hours later, on all adults who underwent CT in the researchers’ health region from January 2006 through May 2013. They used increases in creatinine levels to determine if new acute kidney injury occurred over the course of either time period.

Their results showed that acute kidney injury and dialysis after acute kidney injury resulting from contrast-enhanced CT were statistically insignificant across glomerular filtration rate (GFR) subgroups, with acute kidney injury incidences (Acute Kidney Injury Network stage I or worse) of 0.5 percent for GFR greater than 60 mL/min/1.73 m2; 2.4 percent for GFR 30–59 mL/min/1.73 m2; −4.3 percent for GFR 15–29 mL/min/1.73 m2; and 0 percent for GFR less than 15 mL/min/1.73 m2.

“Although IV contrast material may induce nephropathy, our results suggest that it has a minimal risk of acute kidney injury at all, except possibly the most severe, stages of renal dysfunction,” the authors concluded. “This could lead to its more frequent use in patients with renal dysfunction, which could both increase the diagnostic capacity of CT and avoid the greater cost of other imaging techniques, such as gadolinium-enhanced MRI.”