Users' Guides to the Medical Literature
Guyatt G, Rennie D, Meade MO, Cook DJ
Part B Therapy
Chapter 9.3. Randomized Trials Stopped Early for Benefit
Victor Montori, P. J. Devereaux, Holger Schünemann, Maureen O. Meade, Deborah J. Cook, Gordon Guyatt
Randomized Controlled Trials Stopped Early for Benefit Play a Prominent Role in the Medical Literature
Topics Discussed:
randomized controlled trials, randomized controlled trials, truncated, stopping rules, truncated studies
Excerpt:
"Investigators may stop randomized controlled trials (RCTs) earlier than planned because of perceived harm of
the experimental intervention, because they lose
hope in achieving a positive result, or because the sponsor wishes
to save money.1 The most common reason for early
stopping, however, is that investigators note treatment
effects that appear to be unlikely by chance (and that
are often large) and that persuade them that the experimental intervention
is beneficial. Trials stopped early for apparent
benefit—which we will refer to as truncated RCTs—often
receive considerable attention. They enjoy extraordinary success
in appearing in the most prominent journals and in the popular press,2 markedly
increasing their likelihood of widespread dissemination and subsequent
citation. They may, with remarkable rapidity, form the basis of practice
guidelines and criteria for quality of medical care. Such
has been the fate of stopped-early RCTs documenting
the effect of tight glucose control with insulin in patients in
the intensive care unit3 and 
-blockers
in patients undergoing vascular surgery.4 Moreover,
the frequency of their appearance in the medical literature is growing
rapidly; more than 1% of the RCTs published in
15 leading medical journals from 2000 to 2004 were stopped early for
benefit, a 100% increase in 1 decade.2 Because
authors may not always report that their trial was stopped early,
however, the true frequency may be much greater.5..."
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