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EBM round-up: February 2011
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  1. Richard Saitz
  1. Boston Medical Center, Boston University Schools of Medicine and Public Health, Boston, Massachusetts, USA
  1. Correspondence to Richard Saitz
    Section of General Internal Medicine, Boston Medical Center, Boston University Schools of Medicine and Public Health, 801 Massachusetts Avenue, 2nd floor (Crosstown 2), Boston, MA 02118–2335, USA; rsaitz{at}bmjgroup.com

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Noun (\ˈraund-ˌəp\) 1) the act or process of collecting animals by riding around them and driving them in; 2) a summary of information.

Transitive verb 1) to collect (as cattle) by means of a roundup; 2) to gather in or bring together from various quarters.1

In this occasional feature we gather and summarise articles relevant to the practice, research and teaching of evidence-based medicine (EBM) that have been published elsewhere in the peer-reviewed medical literature. The primary criterion for selection is relevance to EBM. Articles are selected by scanning selected journal tables of contents for reports of potential relevance. The round-up writer (an EBM editor) comments on each summary.

Trials stopped early for benefit overestimate treatment effects

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Data safety monitoring committees are often charged with stopping controlled studies when data suggest a benefit is very likely. Such committees often base decisions on statistical significance using calculations designed specifically for this purpose. But the results of studies stopped early might not be what they would have been had the trial continued. To determine whether treatment effects differed, investigators systematically reviewed the literature to compare outcomes of treatment studies stopped earlier than initially planned due to interim results favouring the intervention, to those in meta-analyses of studies addressing the same question that were not truncated.

Investigators included 91 truncated randomised controlled trials (RCTs) and 424 non-truncated trials of the same question identified in systematic reviews addressing 63 questions. They calculated the ratio of relative risks (RRs) (in other words, the RR of bad outcome in the treatment group compared with control in truncated studies over the RR in non-truncated trials). The ratio was <1 in 55 of 63 comparisons, and the (weighted) average of the ratios was 0.71 (95% CI 0.65 to 0.77). RCTs were more likely to be published in high-impact journals (30% vs 68%). Differences …

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