November 23, 2010 - The preliminary findings of the CREST study have so far failed to squelch the debate between proponents of the two different interventions for preventing stroke in patients with carotid stenosis. And at least one prominent vascular surgeon sees a most-unscientific phenomenon - “presenter bias” - as one reason the controversy is likely to continue.
Funded by the National Institute of Neurological Disorders and Stroke and Abbott Laboratories, the 8-year CREST randomized 2,502 symptomatic and asymptomatic patients with carotid stenosis at 117 centers in the United States and Canada. The primary endpoint for the trial was the 30-day rate of stroke, death and myocardial infarction (MI) combined with the rate of ipsilateral stroke over the following 4 years. Initial data released in February showed no significant difference between the two procedures at a median follow-up (7.2 percent for stenting versus 6.8 percent for surgery).
That hasn’t prevented advocates on either side from staking claims of superiority for their preferred treatment modality. Speaking to hundreds of vascular professionals at the VEITHsymposium, Frank J. Veith, M.D., professor of surgery, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, noted that when the findings have been presented, the conclusions have differed greatly depending on the bias of the presenter.
Carotid endartarectomy (CEA) proponents point to the lower stroke rates and mortality among patients to justify the conclusion that CEA is superior.
Supporters of carotid stenting (CAS), on the other hand, have cited the higher incidence of myocardial infarction in the CEA group along with the equivalent and low overall adverse event rates. Based on this, they say CAS should be used to treat patients who have symptomatic or asymptomatic carotid stenosis.
“The extent to which the preliminary results of CREST are being spun by the proponents of these two diametrically opposed views should be recognized,” Veith said, “and one need not have the wisdom of King Solomon to realize that the truth lies somewhere in between.”
Veith called for patience in interpreting the significance of the findings, citing the need for cost data on the two procedures as well as sub-group analyses that have yet to be published.
While lauding the trial’s design and conduct, he suggested that the study was not without its flaws, and those have played into how the findings are being interpreted and may limit its impact on surgical practice.
He said CAS techniques used in CREST are already outdated, so outcomes for CAS patients may be better under the current regimen, and could improve with new CAS technology. CEA supporters may question whether the CAS outcomes obtained in CREST, whose investigators were exceptionally highly skilled, are likely to be achieved if the procedure is adopted by the vascular surgical community at large. And because it only looked at these two interventions, medical therapy, particularly high-dose statin regimens, may produce better outcomes for some segments of these patients.
He also called for more outcome studies, including those that compare both CEA and CAS with best medical treatment. But that may be some years away, as the eagerly awaited TACIT has yet to be funded.
“Trials have flaws, technology advances, and physicians have biases – whether they recognize them or not,” Veith said. “We need to be aware of all of these factors when evaluating the results presented for even very well designed trials like CREST, so that the ‘spinning’ of data, in whatever direction, does not supplant the healthy questioning and analysis the science deserves.”
For more information: www.VEITHpress.org