Contrast-enhanced CT scans do not increase the risk of kidney failure in patients with acute stroke
Research Activities, February 2011, No. 366
Computed tomography (CT) used with an intravenous contrast agent to diagnose brain blood flow problems in patients with acute stroke does not increase the patient's risk of kidney failure (acute nephropathy, AN), a new study finds. Hospitals typically use contrast-enhanced CT to diagnose blocked or restricted areas of brain blood flow in patients brought to the emergency department (ED) with acute stroke. However, clinicians have been concerned that the use of iodine-containing contrast agents might increase the risk of kidney failure. They compared 575 acute stroke patients at one medical center, who underwent contrast-enhanced CT, with 343 patients who underwent CT scans without contrast. Overall, 5 percent of patients in the contrast-exposed group developed kidney failure compared with 10 percent of the nonexposed group. Significantly higher incidences of AN were observed in the nonexposed group at 24 and 48 hours after their CT scans, but the incidence of AN in the two groups was not significantly different by 72 hours.
After adjusting for age, sex, kidney filtration rate at ED admission, and conditions that increase the risk of using contrast material, the researchers found that contrast-exposed patients were only 42 percent as likely to develop AN as nonexposed patients. Patients receiving contrast agents, who were at high risk of contrast-induced nephropathy (e.g., those with diabetes, cardiovascular disease, or low kidney filtration rates), were pretreated with hydration and N-acetylcysteine. The researchers concluded that the use of intravenous contrast agents is safe for use in CT scans of patients with acute stroke, independent of their initial kidney filtration rate, as long as standard preventive measures are taken. The study was funded in part by the Agency for Healthcare Research and Quality (HS11392).
More details are in "Functional contrast-enhanced CT for evaluation of acute ischemic stroke does not increase the risk of contrast-induced nephropathy," by Fabricio O. Lima, M.D., Michael H. Lev, M.D., R.A. Levy, M.D., and others in the May 2010 American Journal of Neuroradiology 31(5), pp. 817-821.