#Group sequential testing trial#
However, the handling of treatment comparisons while a trial is still in progress poses problems in medical ethics, statistical analysis and practical organization. It would therefore appear that assessment of interim treatment differences is a logical and worthwhile extension. Such monitoring may be undertaken in conjunction with a data and safety monitoring board (DSMB), established to review the information collected. This can range from simple checking of protocol compliance and the accurate completion of record forms, to monitoring adverse events in trials of serious conditions so that prompt action can be taken. Some routine monitoring of trial progress, usually blinded to treatment allocation, is often undertaken as part of a phase III trial. It is natural to be interested in such results, but the uncontrolled examination of data can lead to misleading and sometimes wholly inappropriate conclusions, an issue which is considered further in this article. Here, results from patients who enter the trial early on are available for analysis while later patients are still being enrolled. While such a framework is logical when observations are available simultaneously, as in an agricultural field trial, it may be less suitable for medical studies, in which patients are recruited over months if not years, and data are available sequentially. Data on all patients are then collected before any formal analyses are performed. The traditional approach to conducting phase III clinical trials has been to calculate a single fixed sample size in advance of the study, which depends upon a specified significance level and power and the treatment advantage to be detected. In this paper we show how sequential methodology can play an important role in such trials. Its purpose is to seek firm evidence to support a claim that the experimental treatment has clinical benefits. A phase III clinical trial is a large-scale study, typically comparing a promising experimental treatment with a control (placebo or active).
#Group sequential testing series#
In this, the first in a series of three papers dealing with the opportunities and dangers presented by interim analyses in clinical trials, we focus on phase III clinical studies.
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