What's the Best Treatment for Arterial Blockages?
One of the greatest advances in modern medicine was the realization that doctors’ personal experience is not sufficient evidence for the preference of one treatment to another. The double-blind trial was developed to overcome various kinds of bias and prejudice in both patient and doctor, and on the whole has been a great methodological success. It is not perfect, however.
A trial recently published in the New England Journal of Medicine illustrates this. It was designed to establish whether endarterectomy (the surgical removal of arterial blockage) or stenting (the insertion of a tube and filter) is a better treatment for narrowing of the carotid artery, a condition that leads to strokes.
The trial was carried out in 117 centers in the United States and Canada, by surgeons and interventionists who were certified as having good results beforehand. Eligible patients, of whom there were originally 2502, were divided randomly into those who received endarterectomy and those who were stented. The end points of the trial were stroke, heart attack and death.
There was no difference between the two treatments at four years, but the researchers then extended the follow-up period to ten years. By then, the number of patients who were followed up had dwindled to 1607. 895 of the original patients were not included for various reasons, among them that they had died (186).
The results showed that there was no statistically significant difference in the outcomes. 11.8 per cent of the stented group had any one (or more) of the end points against 9.9 per cent of those who had had endarterectomy. 6.9 per cent of the stented group had had strokes while 5.6 per cent of the endarterectomy had had strokes. Although none of the differences among various sub-groups was statistically significant, they were all slightly in favor of endarterectomy and one has to remember that statistically significant difference is not a measure or real or actual difference; and the authors seemed believe that there was a difference between the two modes of treatment because they attribute the difference to the fact that the patients assigned to stenting were slightly more at risk in the first place.