In Reply.
—To respond fully to the important issues raised in the above letters would vastly exceed the space allotted herein. Consequently, many points will be addressed in subsequent publications (B. Young, W. Moore, J. Robertson, et al, unpublished data, 1995; W. Moore, B. Young, W. Baker, unpublished data, 1995).When the ACAS was initiated in 1985, arteriography had a high complication rate, ultrasound imaging was not well developed, and there was negative sentiment regarding carotid endarterectomy because platelet antiaggregating agents were thought to suffice. Our study reflects these constraints because, once initiated, the ACAS could not be restructured.Dr Foster misunderstands the statistical methods used for contrasting the results of medical with surgical management. When the Monitoring Committee determined that ACAS stopping boundaries had been crossed at a median (not mean) of 2.7 years, our follow-up exceeded 3 years in 44% of patients and 4 years in 26% of