Sample Size Re-estimation with East ADAPT and East SURVADAPT

The Promising Zone: East’s team of statistical experts developed the ‘Promising Zone’ concept to improve statistical power in the absence of established efficacy. The Promising Zone standard is now accepted routinely by regulatory agencies worldwide.

Create efficient, ethical, cost-effective trials with East ADAPT Promising Zone designs. The Promising Zone is also available for survival designs in East SURVADAPT.

Elegant adaptive re-estimation techniques simplify and clarify critical decisions for interim analysis.

Guaranteed Conditional Powerfor Trials in the Promising Zone

Imagine that interim analysis determines that a study’s conditional power lies within the Promising Zone, for example between 30% and 80%. Conditional power can increase significantly with an appropriate increase of sample-size. East provides intricate measurement tools to determine conditional power and novel adaptive techniques to re-estimate sample sizes, ensuring that every trial in the Promising Zone obtains high conditional power.

Adaptive SSR: Debunking the inefficiency myth



Sample Size Re-estimation

  • Adapt trials based on look, number, interim sample size, or information scale
  • Define the Promising Zone based on conditional power, test statistic, or estimated effect size. The Promising Zone allows users to determine increases in sample size given information acquired during the trial.
  • Experiment with multiple adaptation rules and select the best for your trial.
  •  Vary accrual and dropout patterns to perform sensitivity analysis.
  • Fine-tune the design by comparing multiple values of all these parameters.
  • Conditional Power Calculators
  • Accurate analysis at design and interim stage.
  • Useful for early-stopping decisions.
  • Muller and Schafer method for continuous and discrete endpoints
  • Adaptive trials with non-inferiority hypothesis

Trial Simulation Tools

  • Evaluate power and expected sample size of Cui, Hung and Wang method (Biometrics, 1999)
  • Evaluate power and expected sample size of Chen, DeMets and Lan extension (Statistics in Medicine, 2004)
  • Evaluate power and expected sample size of Müller and Schäfer method (Biometrics, 2001)

Promising Zone Case Study


Trial Adaptation Tools

  • Change sample sizes.
  • Modify error spending function.
  • Revise the number and spacing of interim measurements.
  • Refine primary hypothesis.
  • An Interim Monitoring Worksheet specifically for group sequential designs with one sample size reassessment at each interim look
  • Computes the Cui, Hung and Wang weighted statistic at each interim stage
  • Permits unweighted statistic (if the Chen, DeMets and Lan criteria are satisfied)
  • Computes repeated p-values and repeated confidence intervals, adjusted for adaptive changes

Only in East

  • Promising Zone Design
  • Median Unbiased Point Estimates, Confidence Intervals and p-values based on a new publication by Brannath, Mehta and Posch (Biometrics, June 2009). No other software package provides these median unbiased point estimates and their associated confidence intervals.

Learn more about the Valor trial