Optimization of testing times and critical values in sequential equivalence testing

Area of Science:

• Biostatistics
• Clinical Trial Design
• Pharmaceutical Research

Background:

• Interim analyses in long-term clinical trials aim to reduce patient numbers.
• Group sequential designs are a practical method for implementing interim analyses.
• While many trials focus on demonstrating efficacy differences, equivalence trials are increasingly common.

Purpose of the Study:

• To develop and present optimized group sequential test procedures for two-sided equivalence trials.
• To provide guidance on sample size optimization in equivalence trials.
• To offer practical tools for planning interim analyses in equivalence trials.

Main Methods:

• Construction of optimized group sequential designs focusing on sample size behavior.
• Development of tables for optimal testing times and critical values.
• Provision of values for constructing alpha-spending functions.

Main Results:

• Optimized group sequential designs for two-sided equivalence trials were constructed.
• Tables detailing optimal testing times and corresponding critical values are provided.
• Methods for constructing alpha-spending functions tailored for equivalence trials are presented.

Conclusions:

• The presented methods and tables facilitate efficient planning of interim analyses in equivalence trials.
• Optimized group sequential designs can improve sample size efficiency in equivalence studies.
• This work provides a practical framework for conducting equivalence trials with interim analyses.