CORRESPONDENCE: LETTERS TO THE EDITOR
Contrast Nephropathy: Isosmolar and Low-Osmolar Contrast Media
Simona Detrenis, MD*,
Michele Meschi, MD and
Giorgio Savazzi, MD
* Department of Internal Medicine and Nephrology, University of Parma, Via Gramsci, 14, I-43100 Parma, Italy (Email: simonadts{at}libero.it).
We read with interest the meta-analysis by McCullough et al. (1) regarding the lower incidence of contrast-induced nephropathy (CIN) in patients who received isosmolar contrast medium (IOCM) iodixanol, as compared with those who received low-osmolar contrast media (LOCM). Nevertheless, we believe the study presents some important methodological limitations that could reduce its value.
In the meta-analysis, the greater part of the patients (789 of 1,345) included in the group receiving LOCM were given an ionic contrast medium (CM), and only 69 patients received iopamidol, the contrast agent that, according to recent data, seems to be the safest of the LOCM (2,3). Therefore, the results of the meta-analysis could derive from the small number of patients receiving iopamidol in the LOCM group, rather than to the renal safety of isosmolar iodixanol. Moreover, apart from the small meta-analysis by Clauss et al. (4) comparing the nephrotoxicity of the IOCM iotrolan with different types of LOCM (iopamidol, iopromide, and iohexol), the previous major comparative studies supporting the possible safety of IOCM have been performed only between iodixanol and the monomer iohexol (5–7), which is found to be one of the CMs most responsible for CIN (2,3). Thus, at present, we do not perceive any definitive evidence of the presumed advantage derived from the use of IOCM in comparison with all of the LOCM (8).
In addition, the investigators themselves note that only 18.3% of patients included in the meta-analysis had their final creatinine (Cr) values measured on day 3 or later (1), whereas CIN is defined as an increase of serum Cr levels of 0.5 mg/dl (or 44 µmol/l) or a 25% or greater relative increase from baseline 48 to 72 h after a diagnostic or interventional procedure requiring CM administration (9). We would like to understand how the researchers completed Table 4 in their study summarizing the incidence of CIN occurring within 72 h if only 18.3% of patients have their Cr values recorded on day 3.
Finally, as underscored by the investigators (1), another important bias could be identified in the lack of data relative to the amount or type of intravenous hydration prophylactic protocol given before and after CM administration, which could influence the outcomes of each trial (10).
We believe that prospective, double-blind, randomized, controlled trials comparing iodixanol with all LOCM would be necessary to confirm the results of this meta-analysis.
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- McCullough PA, Bertrand ME, Brinker JA, Stacul F. A meta-analysis of the renal safety of isosmolar iodixanol compared with low-osmolar contrast media J Am Coll Cardiol 2006;48:692-699.[Abstract/Free Full Text]
- Solomon R, Dumouchel W. Contrast media and nephropathy: findings from systematic analysis and Food and Drug Administration reports of adverse effects Invest Radiol 2006;41:651-660.[CrossRef][ISI][Medline]
- Solomon R. The role of osmolality in the incidence of contrast-induced nephropathy: a systematic review of angiographic contrast media in high risk patients Kidney Int 2005;68:2256-2263.[CrossRef][ISI][Medline]
- Clauss W, Dinger J, Meissner C. Renal tolerance of iotrolan 280—a meta-analysis of 14 double-blind studies Eur Radiol 1995;5:S79-S84.[Abstract/Free Full Text]
- Chalmers N, Jackson RW. Comparison of iodixanol and iohexol in renal impairment Br J Radiol 1999;72:701-703.[Abstract]
- Aspelin P, Aubry P, Fransson SG, Strasser R, Willenbrock R, Berg KJ. Nephrotoxic effects in high-risk patients undergoing angiography N Engl J Med 2003;348:491-499.[Abstract/Free Full Text]
- Lim P, Mackie K, Ross J, Seidelin P, Dzavik V. Contrast nephropathy and Visipaque use in routine clinical practice of percutaneous coronary intervention: insights from Toronto General Hospital PCI Registry Circulation 2004;110(Suppl 3):III492(abstr).
- Savazzi G, Detrenis S, Meschi M, Musini S. Low-osmolal and iso-osmolal cotrast media in contrast-induced nephropathy Am J Kidney Dis 2005;45:435-436.[ISI][Medline]
- Detrenis S, Meschi M, Musini S, Savazzi G. Lights and shadows on the pathogenesis of contrast-induced nephropathy: state of the art Nephrol Dial Transplant 2005;20:1542-1550.[Free Full Text]
- Meschi M, Detrenis S, Musini S, Strada E, Savazzi G. Facts and fallacies concerning the prevention of contrast medium-induced nephropathy Crit Care Med 2006;34:2060-2068.[CrossRef][ISI][Medline]
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