Written by Clay Smith
Spoon Feed
There was no difference in long term renal function in ED patients who received contrast for CTPA vs those who did not.
Why does this matter?
We have covered the controversy over contrast nephropathy before. Even the radiologists say contrast is OK in most circumstances. Contrast-associated acute kidney injury may be largely fictional. Here is yet another very clever look at this.
In contrast to what you’ve heard…
This was a well designed study that looked at 156,028 patients who had a D-dimer drawn. The idea was that those with results ≥500 ng/mL have a markedly increased chance of getting a CTPA (with IV contrast of course) than those with a result <500. But these patients should be otherwise very similar. This study design is called a regression discontinuity analysis. It is not the same as a RCT and can’t prove causality, but it can provide data that is less likely to be confounded. They found that indeed the two cohorts above and below a D-dimer of 500 were very similar with regard to known confounders. Most importantly, there was no difference in eGFR 6 months after contrast exposure between the two groups. There was also no difference in need for dialysis, mortality, or acute kidney injury between groups. This provides some of the strongest evidence to date demonstrating the safety of IV contrast administration, at least in ED patients getting CTPA.
Source
Association of Intravenous Radiocontrast With Kidney Function: A Regression Discontinuity Analysis. JAMA Intern Med. 2021 Apr 5;e210916. doi: 10.1001/jamainternmed.2021.0916. Online ahead of print.
But these pts have a great GFR. That’s not where the concern is. It’s in those with a lesser GFR, DM, volume depletion and those that may get contrast again, esp arterial. And we shouldn’t give it just for a prettier picture. If you need it to decide what to do give it. If you don’t need it try to use some clinical judgement.