(Stroke. 1998;29:2444-2446.)
© 1998 American Heart Association, Inc.
Letters to the Editor |
Is the Increasing Volume of Carotid Endarterectomy Justified?
Department of Neurology, Wayne State University, Detroit, Michigan
To the Editor:
I read with interest the recent article by Huber et al1 regarding carotid endarterectomy (CEA) volume in Florida since the Asymptomatic Carotid Atherosclerosis Study (ACAS) advisory was released. In this article, the authors made one statement that is unwarranted. They state in the discussion that "the morbidity and mortality rates reported in the study are consistent with those from multicenter carotid endarterectomy trials." However, data from Table 5 of their paper would appear to contradict this assertion.
In the first report of the North American Symptomatic Carotid Endarterectomy Trial (NASCET),2 the mortality was 0.6%. In the ACAS,3 the perioperative mortality was 0.1%. In the study of Huber et al, the mortality in a mixed population of symptomatic and asymptomatic patients between the ages of 75 and 84 was 1.2%. Above age 84, the mortality was 2.2%. The latter value is close to 4 times higher than the NASCET mortality figure and 22 times higher than the ACAS rate. This is hardly comparable to multicenter trials. High rates of perioperative mortality in elderly patients have also recently been reported by Wennberg and colleagues.4 In their analysis of over 100 000 Medicare beneficiaries undergoing CEA in 1992 and 1993, the 30-day mortality rate was 2.46 for patients between the ages of 80 and 84 and 3.60 in patients over age 85.
Huber et al also do not comment on an important issue, namely, the extrapolation of the ACAS results to patients beyond the original study cohort. In the ACAS, the upper age limit was 79. Surgeons in Florida apparently believe that the modest clinical benefit seen in the ACAS can be extended to patients above age 80. The data described above would indicate, however, that there is little justification for operating on elderly, asymptomatic individuals with prevailing community-based perioperative mortality rates.
How should health policy makers respond to the report of Huber and colleagues? Is the additional $56 million spent in Florida money well spent in terms of stroke prevention? In a country in which hypertension is adequately controlled in fewer than 1 in 4 patients, I would suggest that the public health benefits of effectively treating hypertension far exceed the value of CEA on asymptomatic patients using "real world" performance data. In addition, third-party payers may want to reconsider routine reimbursement of CEA on asymptomatic elderly patients, since it is likely that many of these patients are deriving no benefit from the procedure.
References
1.
Huber TS, Wheeler KG, Cuddeback JK, Dame DA, Flynn TC,
Seeger JM. Effect of the Asymptomatic Carotid Atherosclerosis Study on
carotid endarterectomy in Florida. Stroke. 1998;29:1099–1105.
2. North American Symptomatic Carotid Endarterectomy Trial Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade stenosis. N Engl J Med. 1991;325:445–453.[Abstract]
3.
Executive Committee for the Asymptomatic Carotid
Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery
stenosis. JAMA. 1995;273:1421–1428.
4.
Wennberg DE, Lucas FL, Birkmeyer JD, Bredenburg CE, Fisher
ES. Variation in carotid endarterectomy mortality in the Medicare
population. JAMA. 1998;279:1278–1281.
Response
1 Department of Surgery, 3 Department of Hospital Policy and Epidemiology, University of Florida College of Medicine, Gainesville, Florida, 2 Department of Surgery, Gainesville Veterans Administration Medical Center, Gainesville, Florida, 4 Duke University School of Medicine, Durham, North Carolina
We appreciate Dr Chaturvedi's interest in our recent article, "Effect of the Asymptomatic Carotid Atherosclerosis Study on Carotid Endarterectomy in Florida,"1 and appreciate the opportunity to respond. Dr Chaturvedi objected to a sentence in the "Discussion" which stated that "the morbidity and mortality rates reported in the study are consistent with those from multicenter carotid endarterectomy trials." He went on to point out that the mortality rate in those patients >84 years of age was 4-fold greater than that in NASCET and 22-fold greater than in ACAS. Dr Chaturvedi's comments are correct, and the statement merits clarification. Our statement referred to the overall perioperative mortality and central nervous system complication rates (see Table 4 in the article1) over the 5 years of the study rather than those for the various demographic groups. The overall perioperative mortality and central nervous system complication rates ranged from 0.8% to 1.3% and 0.8% to 1.1%, respectively. These values are well within the range of the rates for perioperative mortality (ECST,1 1.0%; NASCET,2 0.6%; VA/Symp,3 3.3%; VA/Asymp,4 1.9%; ACAS,5 0.2%) and combined perioperative stroke/mortality (ECST,1 3.3%; NASCET,2 5.8%; VA/Symp,3 6.5%; VA/Asymp,4 4.7%; ACAS,5 2.3%) reported in the multicenter trials. Although the statement in the Discussion section could have been clarified by referring the reader to the appropriate table, we feel that the objectionable statement was taken somewhat out of context. The remaining sentences in the paragraph that followed the statement outline the limitations of the database and the potential inaccuracy of the morbidity and mortality data. Furthermore, it should be emphasized that patients aged >84 years accounted for only 3.8% of all those in the study and that NASCET and ACAS represent only two of the reported multicenter trials.
Dr Chaturvedi further criticized the manuscript by stating that we failed to comment on the extrapolation of the ACAS data to patients beyond the study cohort, and he stated that our data do not support carotid endarterectomy in elderly, asymptomatic patients. We share Dr Chaturvedi's concerns about the increased procedural volume in patients outside the ACAS cohort and the higher reported morbidity and mortality rates in patients >84 years of age, the group with the largest percent procedural increase. However, we would urge caution regarding the interpretation of our data. Although there was a dramatic increase in the volume of carotid endarterectomies in Florida after release of the ACAS results, it cannot be definitively determined that this was due to an increase in asymptomatic patients, since the indications for the procedure were not available from the database. Furthermore, although the dataset likely underreports the morbidity and mortality rates, these rates do reflect all carotid endarterectomies performed throughout the state, regardless of indication, including those performed for stroke in evolution or in combination with coronary artery bypass. The impact of these higher risk procedures on the morbidity and mortality rates seen in patients >84 years in our study cannot be assessed from the database. Interestingly, we have recently reported that severity of illness, myocardial infarction, and central nervous system complication, but not octogenarian status per se, correlated with mortality after carotid surgery in Veterans Affairs Medical Centers.6 Thus, due to the limitations of the database, we do not feel that our results should be used to justify or incriminate carotid endarterectomy in any selected population.
Last, Dr Chaturvedi asked how the data from our study should be used and whether the additional medical expenditure after release of the ACAS results was worthwhile. He stated that carotid endarterectomy for asymptomatic patients in the "real world" is not as worthwhile as blood pressure control, and he suggested that third-party payers may want to reconsider reimbursement for carotid endarterectomy in asymptomatic elderly patients. We concluded our article with a challenge to further analyze the cost effectiveness of carotid endarterectomy for asymptomatic stenosis and noted that Cronenwett et al8 reported that carotid endarterectomy for asymptomatic stenosis was not cost effective for patients >75 years of age, using a threshold of $50 000/quality-adjusted life-year saved. It is imperative that we continue to reanalyze health care expenditure to assure optimization of our resources. However, the decisions about resource utilization, such as reimbursement for carotid endarterectomy in elderly asymptomatic patients, should be based on data from sound clinical trials rather than opinion, regardless of how strongly held.
References
1. Huber TS, Wheeler KG, Cuddeback JK, Dame DA, Flynn TC, Seeger JM. Effect of the Asymptomatic Carotid Atherosclerosis Study on carotid endarterectomy in Florida. Stroke.. 1998;29:1099–1105.
2. European Carotid Surgery Trialists' Collaborative Group. MCR European Carotid Surgery Trial: interim results for symptomatic patients with severe (70–99%) or with mild (0–29%) carotid stenosis. Lancet. 1991;337:1235–1243.[Medline] [Order article via Infotrieve]
3. North American Symptomatic Carotid Endarterectomy Trial Collaborators. Beneficial effect of carotid endarterectomy in symptomatic patients with high-grade carotid stenosis. N Engl J Med. 1991;325:445–453.
4.
Mayberg MR, Wilson SE, Yatsu F, Weiss DG, Messina L,
Hershey LA, Colling C, Eskridge J, Deykin D, Winn R. Carotid
endarterectomy and prevention of cerebral
ischemia in symptomatic carotid stenosis.
JAMA. 1991;266:3289–3294.
5.
Hobson RW II, Weiss DG, Fields WS, Goldstone J, Moore
WS, Jonathan JB, Wright CB. Efficacy of carotid
endarterectomy for asymptomatic carotid
stenosis. N Engl J Med. 1993;328:221–227.
6. Executive Committee for the Asymptomatic Carotid Atherosclerosis Study. Endarterectomy for asymptomatic carotid artery stenosis. JAMA. 1995;273:1421–1428.
7. Kazmers A, Perkins AJ, Huber TS, Jacobs LA. Carotid surgery in octogenarians in Veterans Affairs Medical Centers. J Surg Res. In press.
8. Cronenwett JL, Birkmeyer JD, Nackman GB, Fillinger MF, Bech FR, Zwolak RM, Walsh DB. Cost-effectiveness of carotid endarterectomy in asymptomatic patients. J Vasc Surg. 1997;25:298–311.[Medline] [Order article via Infotrieve]
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