Cardiorenal Contrast-induced acute kidney injury and clinical outcomes after intra-arterial and intravenous contrast administration: Risk comparison adjusted for patient characteristics by design Judith Kooiman, MSc, a,b Pum A. Le Haen, MD, c Gülçin Gezgin, BSc, a Jean-Paul P. de Vries, MD, PhD, d Doeke Boersma, MD, d Harald F. Brulez, MD, PhD, e Yvo W. Sijpkens, MD, PhD, f Aart J. van der Molen, MD, g Suzanne C. Cannegieter, MD, PhD, h Jaap F. Hamming, MD, i and Menno V. Huisman, MD, PhD a Leiden, The Hague, Nieuwegein, and Amsterdam, The Netherlands Background Direct comparisons between risk of contrast induced acute kidney injury (CI-AKI) after intra-arterial versus intravenous contrast administration are scarce. We estimated and compared the risk of CI-AKI and its clinical course after both modes of contrast administration in patients who underwent both. Methods One hundred seventy patients who received both intra-arterial and intravenous contrast injections within one year between 2001 and 2010 were included. Primary outcome was occurrence of CI-AKI. Secondary outcomes were duration of hospital stay, the need for dialysis, recovery of renal function, and mortality. Results The risk of CI-AKI was 24/170 (14.0%, 95% CI 9.6-20.2) after intra-arterial contrast injection versus 20/170 (11.7%, 95% CI 7.7-17.5) after intravenous contrast administration, which led to a relative risk of 1.2 (95% CI 0.7-2.1). None of the patients had a need for dialysis. Median duration of hospital stay in CI-AKI patients was 15.0 days (2.5-97.5, percentile 1-92) after intra-arterial and 15.5 days (2.5-97.5, percentile 0-38) after intravenous contrast procedures. Renal function recovered after CI-AKI in 13/24 after intra-arterial and in 10/20 patients after intravenous contrast administration. Mortality risks in CI-AKI patients were slightly higher than in non-CI-AKI patients, hazard ratios 1.6 (95% CI 0.7-3.7) for intra-arterial and 1.7 (95% CI 0.7-4.4) for intravenous contrast administration, adjusted for confounders. Conclusion The risk of CI-AKI, and its clinical course was similar after intra-arterial and intravenous contrast media administration, after adjustment by design for patient-related risk factors. (Am Heart J 2013;165:793-799.e1.) Contrast media can cause contrast induced acute kidney injury (CI-AKI), which is one of the major causes of acute kidney injury and is associated with increased mortality, morbidity and a prolonged duration of hospital stay. 1-3 In cohort studies higher incidences of CI-AKI have been reported following intra-arterial contrast administrations than incidences in studies with patients undergoing intravenous contrast-enhanced computed tomography (CT). 4 This raises the question whether there might be a route-dependent CI-AKI risk that is higher following intra-arterial compared with intravenous contrast administration. 4 Whether the risk of CI-AKI is route dependent would be of clinical importance as it may affect the need for CI-AKI preventive measures. Patients receiving intra-arterial contrast injections might be more likely to have comorbidity than patients undergoing intravenous contrast-enhanced CT, such as chronic kidney disease, which in itself are risk factors for CI-AKI. 4 This could partly explain the higher CI-AKI risk after intra-arterial contrast administration, 5 and therefore, direct comparisons between the described incidences are impossible. Although many studies have reported CI-AKI risks following either intra-arterial or intravenous contrast administration, there is a paucity of studies comparing the development of CI-AKI between the two routes of contrast From the a Department of Thrombosis and Haemostasis, Leiden University Medical Center (LUMC), Leiden, The Netherlands, b Department of Nephrology, LUMC, Leiden, The Netherlands, c Department of Radiology, HagaZiekenhuis, The Hague, The Netherlands, d Department of Vascular Surgery, St. Antonius Hospital, Nieuwegein, The Netherlands, e Department of Nephrology, St. Lucas Andreas Hospital, Amsterdam, The Netherlands, f Department of Nephrology, Bronovo Hospital, The Hague, The Netherlands, g Department of Radiology, LUMC, Leiden, The Netherlands, h Department of Clinical Epidemiology, LUMC, Leiden, The Netherlands, and i Department of Vascular Surgery, LUMC, Leiden, The Netherlands. Submitted November 21, 2012; accepted February 17, 2013. Reprint requests: Judith Kooiman, MSc, LUMC, Postzone C4-070, Postbus 9600, 2300 RC Leiden, The Netherlands. E-mail: j.kooiman@lumc.nl 0002-8703/$ - see front matter © 2013, Mosby, Inc. All rights reserved. http://dx.doi.org/10.1016/j.ahj.2013.02.013