To the Editor.
—The title of the article by Dr Oler and colleagues1 is misleading. In this meta-analysis of published data from 6 small randomized trials of aspirin plus heparin vs aspirin alone for patients with unstable angina, no significant reduction of myocardial infarction (MI) or death was reported during the period of randomized treatment (relative risk [RR], 0.67; 95% confidence interval [CI], 0.44-1.02) or, in the subset of 4 studies with data available, during 12 weeks of follow-up (RR 0.82; 95% CI, 0.56-1.20).Moreover, limiting the meta-analysis to trials that published data on MI or death during the treatment period could have produced biased estimates of the effects of treatment because the decision to publish any such data may well have been influenced by the results (and statistical tests for such "publication bias" are insensitive). Further bias might have been introduced into this meta-analysis by the exclusion of
Collins R, Peto R. Benefit of Heparin Plus Aspirin vs Aspirin Alone in Unstable Angina. JAMA. 1996;276(23):1873. doi:10.1001/jama.1996.03540230023014