title: The role of external evidence in data monitoring of a clinical trial.
abstract: Data monitoring of interim results from a randomized clinical trial should take into consideration evidence from other trials. This article presents both scientific and practical issues regarding the pros and cons of formally incorporating such external evidence into the decision making process for the current trial. Guidelines on how to use other trials' data are presented, along with cautiously sceptical comments on the impracticality of using formal meta-analyses in data monitoring. The arguments are illustrated by recent examples from specific trials, and the article concludes with some general recommendations.
authors.affiliation: Medical Statistics Unit, London School of Hygiene and Tropical Medicine, U.K.
authors.forename: S J
authors.initials: SJ
authors.lastname: Pocock
mesh_terms: D003657:Decision Making; D019317:Evidence-Based Medicine; D006801:Humans; D015201:Meta-Analysis as Topic; D010934:Planning Techniques; D016032:Randomized Controlled Trials as Topic; D012107:Research Design