Intravenous Contrast Material Exposure Is Not an Independent Risk Factor for Dialysis or Mortality

Purpose: To determine the risk of emergent dialysis and short-term mortality following intravenous iodinated contrast material exposure. Materials and Methods: This single-center retrospective study was HIPAA compliant and institutional review board approved. All contrast material-enhanced (contrast group) and unenhanced (noncontrast group) abdominal, pelvic, and thoracic computed tomography scans from 2000-2010 were identified. Patients in the contrast and noncontrast groups were compared following propensity score-based 1:1 matching to reduce intergroup selection bias. Patients with preexisting diabetes mellitus, congestive heart failure, or chronic or acute renal failure were identified as high-risk patient subgroups for nephrotoxicity. The effects of contrast material exposure on the rate of acute kidney injury (AKI) (serum creatinine level >= 0.5 mg/dL [44.2 mu mol/L] above baseline within 24-72 hours of exposure) and dialysis or death within 30 days of exposure were determined by using odds ratios (ORs) and covariate-adjusted Cox proportional hazards models. Results were validated with a bootstrapped sensitivity analysis. Results: The 1: 1 matching on the basis of the propensity score yielded a cohort of 21 346 patients (10 673 in the contrast group, 10 673 in the noncontrast group). Within this cohort, the risks of AKI (OR, 0.94; 95% confidence interval [CI]: 0.83, 1.07; P =.38), emergent dialysis (OR, 0.96; 95% CI: 0.54, 1.60; P = .89), and 30-day mortality (hazard ratio [HR], 0.97; 95% CI: 0.87, 1.06; P = .45) were not significantly different between the contrast group and the noncontrast group. Although patients who developed AKI had higher rates of dialysis and mortality, contrast material exposure was not an independent risk factor for either outcome for dialysis (OR, 0.89; 95% CI: 0.40, 2.01; P = .78) or for mortality (HR, 1.03; 95% CI: 0.82, 1.32; P = .63), even among patients with compromised renal function or predisposing comorbidities. Conclusion: Intravenous contrast material administration was not associated with excess risk of AKI, dialysis, or death, even among patients with comorbidities reported to predispose them to nephrotoxicity. (C) RSNA, 2014