Fundamental errors in estimate of lives saved by screening

doi:10.1136/bmj.b3359

Published 25 August 2009, doi:10.1136/bmj.b3359
Cite this as: BMJ 2009;339:b3359

Letters

Breast screening

Fundamental errors in estimate of lives saved by screening

The first 150 words of the full text of this article appear below.

Wald and colleagues estimate that one death from breast canceris avoided for every 100 women screened over 20 years,¹ whichis about 10 times more optimistic than that reported in a comprehensivesystematic review.²

They assume a "generally accepted" 24% reduction in mortalityfrom breast cancer in a population offered screening from aconsensus report of 1993, of which Wald is the first author.³However, this report is little known: PubMed and Web of Sciencedo not index it, and Google Scholar lists 21 citations versus551 for the systematic review.²

Wald and colleagues assume that the 24% would be 30% if everyonehad participated, and use the 30% to calculate the number ofavoided deaths. As not all invited women participate, this ismisleading. It is like saying that if everybody with meningitiswere treated earlier, more would be saved. The authors alsoneglect that attendees are different . . . [Full text of this article]

Karsten J Jørgensen, researcher¹, Peter C Gøtzsche, director¹

¹ The Nordic Cochrane Centre, Rigshospitalet, DK-2100 Copenhagen

kj@cochrane.dk

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