Acute kidney injury in the critically ill: is iodinated contrast medium really harmful?

OBJECTIVES: To assess whether the use of iodinated contrast medium increases the incidence of acute kidney injury in ICU patients, compared with patients not receiving iodinated contrast medium. DESIGN: Prospective observational matched cohort study. SETTING: Two ICUs in two tertiary teaching hospitals. PATIENTS: A total of 380 adults were included (20% more than once), before an iodinated contrast medium infusion (contrast inclusions, n=307) or before an intrahospital transfer without iodinated contrast medium infusion (control inclusions, n=170). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among contrast inclusions, iodinated contrast medium-associated acute kidney injury occurred after 23 administrations (7.5%) according to the Acute Kidney Injury Network definition (stage≥1, over 48 hr). As expected, a broader definition (≥25% increase in serum creatinine over 72 hr) yielded a greater incidence (16%). In 146 pairs of contrast and control inclusions, matched on propensity for iodinated contrast medium infusion, the incidence of acute kidney injury was similar (absolute difference in incidence, 0%; 95% confidence interval, -5.2; 5.2%), Acute Kidney Injury Network definition). Hospital mortality was also similar in 71 contrast and 71 control patients included only once and matched the same way. Contrary to iodinated contrast medium infusion (odds ratio, 1.57; 95% confidence interval, 0.69-3.53), the Sequential Organ Failure Assessment score at inclusion (odds ratio, 1.18; 95% confidence interval, 1.07-1.31) and the number of other nephrotoxic agents (odds ratio, 1.38; 95% confidence interval, 1.03-1.85) were independent risk factors for acute kidney injury. CONCLUSIONS: The specific toxic effect of monomeric nonionic low-osmolar iodinated contrast medium in ICU patients with multiple renal aggressions seemed minimal. Severity of disease and the global nephrotoxic burden were risk factors for acute kidney injury, regardless of iodinated contrast medium infusion.