Correspondence
Prevention of Radiocontrast-Induced Renal Insufficiency
N Engl J Med 1995; 332:1035-1036April 13, 1995
- Article
To the Editor:
The article by Solomon et al. (Nov. 24 issue)1 concerning renal dysfunction induced by radiocontrast agents was interesting, but the authors should have included information about the use of angiotensin-converting–enzyme inhibitors and nonsteroidal antiinflammatory drugs in the three groups of patients. How many of the patients with congestive heart failure or diabetes mellitus and nephropathy were receiving an angiotensin-converting–enzyme inhibitor? Also, how many were receiving aspirin or another nonsteroidal antiinflammatory drug? Both these classes of drugs alter the renal response to changes in arterial volume and therefore could be confounding variables in the study.
1 ReferencesMark J. Shumate, M.D., M.P.H.
Emory University, Decatur, GA 300331
Solomon R ,Werner C ,Mann D ,D'Elia J ,Silva P . Effects of saline, mannitol, and furosemide on acute decreases in renal function induced by radiocontrast agents. N Engl J Med 1994;331:1416-1420
Full Text | Web of Science | Medline
To the Editor:
The study by Solomon et al. was well designed, but we have several reservations about the selection of low-risk patients, the imbalance in the assignment of the few high-risk patients, the use of parametric statistical methods, and the lack of a control group.
First, the risk of acute decreases in renal function in most of the patients was low, because most had serum creatinine concentrations below 2.0 mg per deciliter before angiography. The changes after angiography are consistent with this low risk; very few of the patients had acute decreases in renal function (only 26 percent had an increase in the serum creatinine concentration of at least 0.5 mg per deciliter).
Second, the numbers of high-risk patients in the three study groups varied. There were only 3 patients in the saline group who had serum creatinine concentrations above 2.5 mg per deciliter, as compared with 6 in the mannitol group and 4 in the furosemide group, and these 13 patients accounted for most of the patients who had postangiographic increases in serum creatinine. Thus, the presence of more patients with elevated serum creatinine concentrations in the mannitol and furosemide groups may explain the differences between the three groups.
Third, the use of a parametric test to compare the three groups may be problematic. The changes in serum creatinine concentrations are probably not normally distributed, and there were more patients with elevated concentrations in the mannitol and furosemide groups. Thus, comparing mean values between treatment groups may lead to erroneous conclusions. Finally, it is unclear whether any intervention is better than no intervention at all, because of the lack of a control group.
Louise Pilote, M.D., M.P.H.
Mark J. Eisenberg, M.D., M.P.H.
Cleveland Clinic Foundation, Cleveland, OH 44195Author/Editor Response
The authors reply:
To the Editor: Dr. Shumate correctly points out that both angiotensin-converting–enzyme inhibitors and nonsteroidal antiinflammatory drugs can influence renal hemodynamics and that their use might therefore be expected to influence the incidence of acute renal insufficiency after the administration of radiocontrast agents. Indeed, for this very reason, nonsteroidal antiinflammatory drugs have been used in studies of animals with renal insufficiency induced by such agents.1,2 There were no significant differences in the frequency of therapy with either class of drugs in the three groups in our study.
We agree with Drs. Pilote and Eisenberg that patients with higher base-line serum creatinine concentrations have a greater risk of acute renal insufficiency induced by radiocontrast agents. Indeed, it occurred in 10 of 13 patients (77 percent) with a base-line serum creatinine concentration above 2.5 mg per deciliter but in only 10 of 63 patients (16 percent) with a lower base-line concentration. This is not likely to influence the conclusions of the study. After we excluded patients with a base-line serum creatinine concentration above 2.5 mg per deciliter from the analysis, we still found significant differences between the saline and furosemide groups using nonparametric analysis. For example, an increase of at least 0.5 mg per deciliter in the serum creatinine concentration — our definition of acute renal insufficiency induced by radiocontrast agents — in patients with a base-line serum creatinine concentration of <2.5 mg per deciliter occurred in 4 percent and 28 percent of the patients in the saline and furosemide groups, respectively (P = 0.04). Finally, we do not know whether patients receiving no treatment would have fared differently. Although no prospective, randomized trials have addressed this question, the studies by Eisenberg et al.3 and Brown et al.4 support the use of hydration in patients receiving radiocontrast agents, as do the results of studies in animals.5
5 ReferencesRichard Solomon, M.D.
John D'Elia, M.D.
Denise Mann, R.N.
Joslin Diabetes Center, Boston, MA 022151
Vari RC ,Natarajan LA ,Whitescarver SA ,Jackson BA ,Ott CE . Induction, prevention and mechanisms of contrast media-induced acute renal failure. Kidney Int 1988;33:699-707
CrossRef | Web of Science | Medline2
Heyman SN ,Brezis M ,Epstein FH ,Spokes K ,Silva P ,Rosen S . Early renal medullary hypoxic injury from radiocontrast and indomethacin. Kidney Int 1991;40:632-642
CrossRef | Web of Science | Medline3
Eisenberg RL ,Bank WO ,Hedgock MW . Renal failure after major angiography can be avoided with hydration. AJR Am J Roentgenol 1981;136:859-861
Web of Science | Medline4
Brown RS ,Ransil B ,Clark BA . Prehydration protects against contrast nephropathy in high risk patients undergoing cardiac catheterization. J Am Soc Nephrol 1990;1:330-330 abstract.5
Brezis M, Rosen S, Epstein FH. Acute renal failure. In: Brenner BM, Rector FC Jr, eds. The kidney. 4th ed. Vol. 1. Philadelphia: W.B. Saunders, 1991:993-1061.
