Concerns Regarding Carotid Endarterectomy Guidelines
To the Editor:
We were surprised to read the rather unequivocal endorsement1 by the American Heart Association writing group of carotid endarterectomy (CE) for asymptomatic stenosis of greater than 60%. This position does not represent the viewpoint of all stroke neurologists or surgeons, and some professional groups have recently come to the exact opposite conclusion, not recommending CE for asymptomatic stenosis.2
The writing group states that CE is beneficial if the surgical complication rate is less than 3%. Current evidence indicates that CE complication rates are not being closely monitored at US hospitals.3 A recent study found that the surgical complication rates were either unknown or not being monitored at over 50% of teaching hospitals in the United States.4 In the “real world” of CE practice, it is unlikely that a complication rate this low can be uniformly achieved, and a 1991 analysis of Medicare data found that the death rate associated with CE was 2.3%.5
In addition, we and others have concerns that the Asymptomatic Carotid Atherosclerosis Study (ACAS) results cannot be generalized.6 7 8 9 Only 4% of the eligible patients were entered into the study.10 In addition, 29% of the surgeons who applied for participation in the trial were either rejected or did not complete the credentialing process.11 Thus, in the ideal setting for producing a positive surgical result (namely, combining low-surgical-risk patients with surgeons vetted for their excellence), a statistically significant result was obtained, which may not be clinically meaningful to all clinicians.
Finally, for full disclosure, it would be of interest to know how many members of the writing group were actual ACAS participants. This may affect the panel’s objectivity, and we would suggest that when controversial studies are involved, future writing groups should include a balance between study participants and nonparticipants.
- Copyright © 1998 by American Heart Association
Biller J, Feinberg WM, Castaldo JE, Whittemore AD, Harbaugh RE, Dempsey RJ, Caplan LR, Kresowik TF, Matchar DB, Toole JF, Easton JD, Adams HP Jr, Brass LM, Hobson RW II, Brott TG, Sternau L. Guidelines for carotid endarterectomy: a statement for healthcare professionals from a special writing group of the Stroke Council, American Heart Association. Stroke.. 1998;29:554–562.
Goldstein LB, Moore WS, Robertson JT, Chaturvedi S. Complication rates for carotid endarterectomy: a call to action. Stroke.. 1997;28:889–890.
Chaturvedi S, Femino L. Are carotid endarterectomy complication rates being monitored? Neurology. In press.
Dyken ML. Controversies in stroke: past and present. Stroke.. 1993;24:1251–1258.
Barnett HJM, Eliasziw M, Meldrum HE, Taylor DW. Do the facts and figures warrant a 10-fold increase in the performance of carotid endarterectomy on asymptomatic patients? Neurology.. 1996;46:603–608.
Hennerici M, Drafferttstrofer M, Meairs S. Concerns about generalisation of premature ACAS recommendations for carotid endarterectomy. Lancet.. 1995;345:1041. Letter.
Chaturvedi S, Halliday A. Is another clinical trial warranted regarding endarterectomy for asymptomatic carotid stenosis? Cerebrovasc Dis. In press.
Moore WS, Vescera CL, Robertson JT, Baker WH, Howard VJ, Toole JF. Selection process for surgeons in the Asymptomatic Carotid Atherosclerosis Study. Stroke.. 1991;22:1353–1357.
I believe that every member of the writing committee was and is intimately familiar with all of the arguments advanced by both the ACAS supporters and the ACAS detractors. Nevertheless, the ACAS study is level I evidence (grade A recommendation) that documented a statistically significant benefit of CEA for stroke prevention in patients with ≥60% diameter reduction asymptomatic carotid stenosis. We can argue forever about the clinical significance of this finding, but it does not change the conclusions of the study. We did not use terms such as “so compelling” or “unequivocally,” but rather outlined the rules of evidence used and presented that study as well as other studies in the context of those rules. As noted in the paragraph above the recommendation, “ … some investigators consider it acceptable to delay surgery until there is >80% carotid stenosis …” we assume that Drs Chaturvedi and Halliday and many other distinguished and respected colleagues fall into that category. In short, we believe the statement in the AHA guidelines is evidence based and perfectly reasonable.
The writing group was composed of a well-balanced panel of recognized experts in carotid artery disease from the disciplines of neurology, vascular surgery, and neurosurgery. Parenthetically, we believe the composition of the writing group is irrelevant if an evidence-based approach to guidelines development is used. That is the value of such methodology.
The relative clinical benefits of CEA for severe and moderate symptomatic stenosis and asymptomatic stenosis are well known. The data alone do not help us decide where to draw the line that divides a “worthwhile” procedure from one that is “not indicated” from a cost-to-benefit analysis viewpoint. We believe that kind of decision requires economic, social, ethical, and political analysis, and it was considered beyond the scope of this guidelines paper.
We do not recommend the blanket use of carotid endarterectomy in asymptomatic populations of patients in our AHA report. We simply endorse surgery on asymptomatic patients with ≥60% diameter stenosis by a surgeon who does surgery with <3% risk. We cannot be held responsible for people who misapply guidelines, whether it be this set of guidelines or any other set of guidelines.
The statement that only 4% of eligible patients were entered in the study is not true. The JAMA article states that 42 000 patients were screened and 1662 patients randomized.R1 Screened means evaluated to determine eligibility. Study participants were screened from ultrasound vascular labs, and many patients were not eligible because of symptomatic status, degree of stenosis, or other reasons. Complete data on exclusion criteria were not provided in the manuscript.
In short, we think that the AHA CEA Guidelines are, by and large, evidence based and do not need to be amended. While investigators may respond to any scientific study with their own degree of questions, we think the facts on this speak very clearly for themselves, and we endorse that result unless otherwise equally careful studies suggest an alternative result.
Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid stenosis. JAMA. 1995;273:1421–1428.