Correspondence

Patency Rates for AK Femoropopliteal Bypass To the Editor:

The July 1990 issue of the Annals of Vascular Surgery contains an article by Patterson and associates entitled "Preferential Use of e P T F E for A b o v e - K n e e Femoropopliteal Bypass Grafts." As I was reading this article I was struck by what seems to be an error in the calculation of patency rates by the authors. Specifically, based on the life table data presented in Table 1, patency at 12 months is actually 70% and not 75%, patency at three years is actually 54% and not 61% and patency at five years is actually 50% not 54%. The authors have reported patency at the start of the period rather than at the end of the period (using the same method of interpreting data, patency at one month would have been reported as 100%, although 12 grafts failed during the first month). They also report the secondary patency of 82%, 67% and 56% at one, three

and five years respectively, but it is not possible to assess the accuracy of those patency rates since the data on which they are based is not presented. While these discrepancies do not materially affect the conclusions of the study, they do raise concerns about the accuracy of the results being reported.

Sincerely, Martin L. Schulman, MD Department of Vascular Surgery State University of New York at Stony Brook

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Patency rates for AK femoropopliteal bypass.

Correspondence Patency Rates for AK Femoropopliteal Bypass To the Editor: The July 1990 issue of the Annals of Vascular Surgery contains an article...
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