Radiographic Contrast-Induced Nephropathy and Patient Mortality–1

Abstract

To the Editor: We read with great interest the article by From et al1From AM Bartholmai BJ Williams AW Cha SS McDonald FS Mortality associated with nephropathy after radiographic contrast exposure.Mayo Clin Proc. 2008; 83: 1095-1100Abstract Full Text Full Text PDF PubMed Scopus (141) Google Scholar who evaluated the risk of mortality after contrast-induced nephropathy (CIN). In agreement with previous studies,2McCullough PA Wolyn R Rocher LL Levin RN O'Neill WW Acute renal failure after coronary intervention: incidence, risk factors, and relationship to mortality.Am J Med. 1997 Nov; 103: 368-375Abstract Full Text Full Text PDF PubMed Scopus (1473) Google Scholar, 3Rihal CS Textor SC Grill DE et al.Incidence and prognostic importance of acute renal failure after percutaneous coronary intervention.Circulation. 2002; 105: 2259-2264Crossref PubMed Scopus (1458) Google Scholar, 4Bouzas-Mosquera A Vázquez-Rodríguez JM Calviño-Santos R et al.Contrast-induced nephropathy and acute renal failure following emergent cardiac catheterization: incidence, risk factors and prognosis [in Spanish].Rev Esp Cardiol. 2007; 60: 1026-1034Crossref PubMed Scopus (61) Google Scholar the authors found that CIN was associated with a higher adjusted mortality rate. The more surprising result is that this risk was found to be higher in patients in whom contrast medium was given intravenously than in those in whom it was administered intra-arterially. Because previous data suggest that contrast media may be more nephrotoxic when given intra-arterially,5Davidson C Stacul F McCullough PA CIN Consensus Working Panel et al.Contrast medium use.Am J Cardiol. 2006 Sep 18; 98 (Epub 2006 Mar 2.): 42K-58KAbstract Full Text Full Text PDF PubMed Scopus (150) Google Scholar it is not straightforward to ascribe such differences in mortality to the route of administration of contrast media alone. One possible explanation for these results is incomplete assessment or control of confounding variables. As the authors acknowledge, patients included in the study were not consecutive, and the reason for performing a postprocedural creatinine check-and thus being eligible for the study-may have depended on the baseline risk of the patients and even on their clinical evolution after the procedures. Furthermore, the degree of this selection bias may not have necessarily been similar in the different subgroups, and patients undergoing certain procedures might have been more prone to have their creatinine levels routinely checked. Thus, it would have been illuminating if the authors had provided information on the availability of postprocedural creatinine data in the populations from which the samples were taken. The route of administration of contrast media is specific for each procedure, and the reasons for performing the different procedures may also be related to outcome. As shown in Figure 2 in the study by From et al, the 30-day mortality rate was higher in patients in whom contrast media was given intravenously compared with those in whom contrast media was administered intra-arterially, even in the subgroups not developing CIN. These limitations may preclude an appropriate evaluation of the effect of the route of administration of contrast media on outcome. Radiographic Contrast-Induced Nephropathy and Patient Mortality–2Mayo Clinic ProceedingsVol. 83Issue 12PreviewTo the Editor: I read with interest the article by From et al on mortality due to CIN. The 2-year retrospective analysis showed an odds ratio of increased 30-day mortality of 3.37 (95% confidence interval, 2.58-4.41; P<.001) in patients who developed CIN. Dialysis was needed in 2 patients with CIN, at 122 and 539 days, respectively, after exposure to contrast media. Of note, in 95% of the study patients, low-osmolar contrast media were used. Full-Text PDF Radiographic Contrast-Induced Nephropathy and Patient Mortality–Reply–IMayo Clinic ProceedingsVol. 83Issue 12PreviewWe appreciate the comments by Onuigbo and agree that nephrotoxicity is often multifactorial and may be accentuated by the presence of other medical factors or toxic agents. Furthermore, the need for identifying the highest-risk patients and avoiding, if possible, procedures that require contrast medium is perhaps the safest plan of care at this time. Ultrasonography, noncontrast computed tomography, magnetic resonance imaging, or other evaluation techniques should be considered for these patients if the clinical question requiring imaging can be answered with less risk to the patient than that posed by contrast administration. Full-Text PDF