BMJ  2003;327:752 (27 September), doi:10.1136/bmj.327.7417.752-b

Letter

Interpretation of randomised trials is indeed open to debate

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

EDITOR—McCormack and Greenhalgh once argued that the interpretation of randomised controlled trials is open to debate.1 A recent BMJ news item featuring an overly favourable comment on the diabetes subtrial of the heart protection study illustrates this perfectly.2-4 We question the study's relevance to general practice on four points.

Generalisibility—The diabetes subtrial is part of the main study published in 2002. The researchers in the original trial excluded more than two thirds of the original 63 603 patients. Most of them opted out or were deemed not to be reliably compliant for the trial.

Bias—Analysis of the study's design raises the possibility of a non-match between treatment and control group5; there is a potentially important difference in the dropout rate.

Merging the boundaries—Both studies look at patients with and without preexisting cardiovascular disease. This is misleading as patients with established disease have a higher . . . [Full text of this article]

Philipp Conradi, full time principal in general practice

Maypole Health Centre, Birmingham B14 5DH pconradi@hotmail.com

David Taylor, full time principal in general practice

Woodland Road Surgery, Birmingham B31 2HZ


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