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5th Annual Janice Pogue Lectureship - Janet Wittes: Interim Analyses: Rules or Guidelines – A Guide from and for the Perplexed
Those of us involved in randomized controlled trials, especially trials that test the effect of an intervention on a hard clinical outcome, are conversant with formal interim analyses permitting a DSMB to recommend stopping a trial if there is little hope that the experimental intervention will show convincing evidence of benefit (a.k.a. futility) or if the data show “overwhelming” evidence of benefit. Hidden behind the word “overwhelming” lurks the need to protect the Type I error rate whether one formulates the trial in a frequentist or Bayesian manner. Sometimes, however, the data from a trial do not obey what the designers anticipated. A boundary may be crossed allowing a formal declaration of benefit, but the DSMB is hesitant to recommend stopping because it fears that the trial has still not answered important questions. In other cases, the data show extremely strong evidence of benefit, but the trajectory of the observed trend has not crossed a boundary. This talk uses examples, two from studies performed by PHRI, to address both problems: (a) crossing a boundary that allows a formal declaration of efficacy but not wanting to stop and (b) not crossing a boundary but feeling the data are so strong that continuing is unscientific. In these situations, the DSMB faces a perplexing question: is the defined statistical boundary a rule or a guideline?

Jun 28, 2022 05:00 PM in Eastern Time (US and Canada)

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