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Dr Wesley S. Moore (Los Angeles, Calif). Dr Rockman, that was an excellent presentation and a very carefully analyzed dataset. I think it's going to be extremely helpful to those of us who are trying to justify carrying out carotid duplex scan screening of patients who have appropriate risk factors.

This screening program is somewhat reminiscent of screening for patients with abdominal aortic aneurysm. In those instances, while the occurrence of small aneurysms, and perhaps small carotid stenoses, was fairly common, the number of patients who actually had lesions that were appropriate for surgery was few.

I wonder if you can share with us this morning the percentage of patients who had lesions perhaps in the 60% to 79%, or perhaps the 80% to 99% stenosis category, which would have demanded surgical treatment early on, as opposed to those who have lesions that will just simply be followed up.

Dr Caron B. Rockman. Thank you for those comments, Dr. Moore.

I must tell you that unfortunately it's quite difficult when you screen patients to obtain ideal follow-up. We make recommendations to the patients and their primary care practitioners to get a formal carotid duplex scan, but the patients did not always follow up with that recommendation.

However, we did get formal duplex scans on nearly 90% of these patients. We identified one patient with a carotid occlusion. There were actually no patients in this series who had a severe stenosis in the 80% to 99% range; we did not stratify in the moderate range between 50% and 60%, and 60% and 79%.

That could be considered a criticism of our screening in that we haven't identified patients who need carotid intervention right now. But I would counter that by saying that we're not doing this to simply identify surgical patients, but to increase overall patient awareness and national awareness of stroke that there are ways to prevent strokes from occurring.

Dr John J. Ricotta (Stony Brook, NY). You said there was no relationship to age. That is not only counterintuitive, but flies in the face of a lot of other data that suggest that carotid stenosis is associated with age.

What was the age range of your screening population? Do you think that you failed to find a correlation because of the age range of the screening?

Dr Rockman. I think so. I think we really have selected out our older patients to begin with, and that's why we didn't find a relationship. Our age range was 60 to 90. In our analysis, we examined age both as a continuous variable with t test analysis as well as by dividing the patients into two sections based on 80 years of age. There was still no statistically significant relationship.

Other studies have found a very significant relationship between age and the prevalence of carotid artery disease. However, most of those screening studies have screened patients who are much younger. I believe we probably selected our population to begin with, and within this particular population there was no relationship noted.

Dr Ricotta. Well, Nick Kouchoukos's data actually show over 60, a very nice increase with age. You might want to look at age as a continuous variable.

Dr John Blebea (Hershey, Pa). I think it is important in reviewing these data to emphasize that when we, as surgeons, talk about screening, we are assuming that risk factors exist in the people who are being examined. We are not screening just anyone walking in through the door. That is important because others do not necessarily share that assumption when the term “screening” is used.

As recently as last week at the American Institute of Ultrasound in Medicine annual meeting, the Committee on Standards reviewed and approved a policy statement concluding that screening of asymptomatic patients for carotid disease is not justified. However, it was recognized that people with identified risk factors are justified in undergoing screening. Therefore studies such as these are important in identifying and documenting that there are population factors for carotid disease. When we talk about and propose screening programs, therefore, we are not talking about general population screening programs but screening of people with identified risk factors.

I also have a question to ask you. I recognize the need to measure the blood pressure in studies such as these, to document the presence of hypertension. But do you, in fact, need to do that? If such a screening program is to be instituted more broadly, is a history alone of hypertension sufficient to define the person to be at high risk for carotid arterial disease?

Dr Rockman. I think, in answer to your second question, a history of hypertension alone probably is sufficient. I also think, frankly, it's difficult to make a definitive diagnosis of new hypertension based on one blood pressure measurement. It's true that if we can eliminate the blood pressure measurement at the screening, we may be able to further streamline the process.

I also agree completely with your first statement. I think also, as surgeons, we have to take an overall interest in stroke prevention and can't just present to people that we're just trying to identify patients to operate on; we need to see this problem as a more global issue.

Dr William R. Flinn (Baltimore, Md). Dr Rockman, we are indebted to your group for stimulating this interest in screening for vascular disease nationally. Your patient population is very similar to the population of the AVA national screening program in that it was more than 60% women. You did not find that carotid stenosis was more common in men than women in your screening study, which is unusual, considering our presumption that atherosclerosis is always more common in men. Is it your feeling that, like heart disease, vascular disease, and carotid disease specifically, is underdiagnosed and undertreated, specifically in women, in our population?

Dr Rockman. I think that's an interesting point. Thank you, Dr Flinn.

Certainly our screening population is about 65% women. We can all speculate on what the reasons for this gender distribution may be. It may have something to do with where the advertisements and the publicity for these screenings are placed.

We did not find gender to be a specific factor for a risk of an overall positive screening test or of occult carotid artery disease alone. However, despite traditional demographics that show an increased risk for atherosclerotic disease in the male population, there is still a very significant prevalence in women. I believe it's an important issue that needs additional attention.

Dr George Lavenson (Visalia, Calif). I'd like to congratulate Dr Rockman and the NYU group, not only for your presentation but also for your leadership role in helping to evaluate and to establish national stroke prevention screening.

In our area, the San Joaquin Valley in Central California, which is more rural and has a high stroke rate—it's a stroke belt—we do find that a significant number of those screened have carotid stenosis in the 80% to 99% category. And the more rural we get, the higher the yield. We have had up to 20% to 30% yield with greater than 50% stenosis. We have had some patients with high-grade stenosis who during surgery under local anesthesia did not tolerate occlusion, and surely would have had stroke with any progression of that nearly completely occluding lesion if it had not been found and removed.

So I'd really like to congratulate you and ask what your plans are for further continuance of your stroke screening studies and further establishment of stroke screening nationally.

Dr Rockman. Thank you, Dr. Lavenson, for those comments, and we appreciate your work in this area.

An additional criticism of our work may be that our population is relatively homogeneous with regard to socioeconomic class and race. We plan to take these screenings out into the community to have more ethnic and racial diversity and to provide outreach to socioeconomically disadvantaged populations.