nTerim

Power and Sample Size for Group Sequential Trials

Clinical Trials are Longitudinal……….. Why Wait to Take a Look??
By their very nature, almost all clinical trials are longitudinal. It is practically impossible to recruit, enrol and randomize all the required subjects at exactly the same time. Therefore, subjects and their subsequent data are accumulated sequentially over time. Sometimes, instead of using fixed period trial methodology, researchers find it necessary (or even desirable) to employ a group sequential design with a number of planned interim analyses in a clinical trial.

Efficacy & Economics Together……..A Powerful Force!!
Sequential statistical methods have been developing over recent decades for ethical, administrative and economic reasons. In human and animal trials, it is essential to monitor results to ensure that the subjects are not exposed to unsafe, inferior or ineffective treatments. Equally, if a trial is showing a very positive result of overwhelming efficacy, early stopping means that a new product can be brought to market sooner. Thus saving time, money and other equally scarce resources.

nTerim Software……..Power & Sample Size for Group Sequential Trials
But group sequential designs present particular challenges when attempting to calculate sample size and power. nTerim has been developed to provide power and sample size calculations for group sequential trials. The sample size and power calculations in nTerim use the alpha spending function method of Lan & DeMets, and include the spending functions from O’Brien & Fleming, Pocock, Hwang-Shih-DeCani, and others.

nTerim……… Main features and highlights include

• Power and Sample Size calculations for Two Means test, Two Proportions test and Log Rank test.
• Choice of four alpha spending functions, O’Brien-Fleming, Pocock, Hwang-Shih-DeCani and Power as well as option to manually specify boundaries.
• Plots of boundary values.
• Plots of power vs sample size.
• Output statement detailing the parameters involved in the trial.
• Detailed analysis of alpha spending and power at each interim ‘look’.
• Easy to use spreadsheet style interface.
• Interactive Help and input advice.
• Customizable screen layout and configuration.

Watch our 2 minute nTerim introductory video now