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Contrast nephropathy in patients with impaired renal function: high versus low osmolar media
B J Barrett1, P S Parfrey, H M Vavasour
1Department of Medicine, General Hospital, St. John's, Newfoundland, Canada.
Insights
Low osmolar contrast did not significantly reduce contrast nephropathy in patients with renal impairment compared to high osmolar contrast. Risk factors include diabetes and severity of pre-existing kidney disease.
Area of Science:
- Nephrology
- Radiology
- Clinical Trials
Background:
- Contrast-induced nephropathy (CIN) is a risk in patients with renal impairment.
- Low osmolar contrast media are often prescribed to prevent CIN, but their cost-effectiveness and efficacy are debated.
Purpose of the Study:
- To compare the incidence of contrast nephropathy between high and low osmolar contrast media in patients with pre-existing renal impairment.
Main Methods:
- A randomized controlled trial involving 249 subjects with serum creatinine > 120 µmol/L undergoing procedures with contrast media.
- Comparison of serum creatinine rise 48-72 hours post-contrast between high and low osmolar contrast groups.
- A non-randomized prospective arm included an additional 117 patients.
Main Results:
- No significant difference in the incidence of a ≥25% rise in serum creatinine between high (6.8%) and low (3.8%) osmolar contrast groups (P > 0.05).
- Severe renal failure (≥50% creatinine increase) was uncommon in both groups.
- Increased risk of CIN was associated with pre-contrast renal impairment severity and diabetes mellitus, particularly in diabetics with creatinine > 200 µmol/L.
Conclusions:
- The incidence of contrast nephropathy was not significantly different between high and low osmolar contrast media in patients with moderate renal impairment.
- The benefit of nonionic contrast in moderate renal impairment is likely small.
- Urgent trials are needed for diabetics with severe renal impairment.
Abstract:
Prescription of low osmolar contrast to prevent nephrotoxicity in subjects with pre-existing renal impairment is costly and has not been clearly shown to be effective. We entered 249 subjects with a pre-contrast serum creatinine greater than 120 mumol/liter (1.35 mg/dl) having cardiac catheterization or intravenous contrast into a randomized controlled trial comparing high and low osmolar contrast. The outcome assessed was a rise in serum creatinine repeated 48 to 72 hours after contrast. A further 117 patients entered the non-randomized prospective arm of the study. In the randomized study the serum creatinine rose by at least 25% after contrast in 8 of 117 (6.8%) given high and in 5 of 132 (3.8%) given low osmolar contrast (P greater than 0.05, one-tailed 95% confidence interval for the difference 3 to 7.8%). More severe renal failure (greater than 50% increase in serum creatinine) after contrast was uncommon (3.4% with high and 1.5% with low osmolar contrast). A rise in serum creatinine after contrast was significantly associated with the severity of the pre-contrast renal impairment and the presence of diabetes mellitus, but not with type of contrast. Diabetics with a serum creatinine greater than 200 mumol/liter (2.25 mg/dl) pre-contrast had a highest risk of deterioration in renal function after contrast. We conclude that in patients with pre-existing renal impairment the incidence of contrast nephropathy was not significantly different comparing high osmolar and nonionic contrast. The potential benefit of nonionic contrast in moderate renal impairment is likely to be small, but trials in diabetics with severe renal impairment should be undertaken urgently.