The fall and rise of carotid endarterectomy in the United States and Canada

Background — Randomized clinical trials have demonstrated the efficacy of carotid endarterectomy in the prevention of stroke when the procedure is performed in regional centers of surgical excellence. However, the relative effects of these studies on the rates of carotid endarterectomy in the United States and Canada have been unclear.

Methods — We calculated the annual rate of carotid endarterectomy in the U.S. states of California and New York and in the Canadian province of Ontario from 1983 through 1995. We also studied whether patients in the early 1990s were selectively referred to hospitals with high volumes of procedures and historically low in-hospital mortality rates.

Results — Rates of carotid endarterectomy fell in all three regions from 1984 to 1989 (from 126 to 66 per 100,000 adults 40 years of age or older in California, from 65 to 40 per 100,000 in New York, and from 40 to 15 per 100,000 in Ontario), after the publication of studies demonstrating that the rates of complications of carotid endarterectomy were unacceptably high. However, the clinical trials of the 1990s, which showed benefit from carotid endarterectomy, were associated with a dramatic resurgence in the rates of the procedure from 1989 to 1995 (from 66 to 99 per 100,000 in California, from 40 to 96 per 100,000 in New York, and from 15 to 38 per 100,000 in Ontario). These increased rates were not associated with proportionally greater numbers of referrals of patients to hospitals with low mortality rates.

Conclusions — There have been a dramatic fall and rise in the rates of carotid endarterectomy in both the United States and Canada, which correlate with the publication of first unfavorable and then favorable clinical studies. The absence of selective referral of patients to centers with the lowest mortality rates raises questions about whether the benefits of carotid endarterectomy in the general population are similar to those demonstrated in the clinical trials.