## PowerTOST & FDA [Power / Sample Size]

Hi Willem,

❝ Could you elaborate on your note of the use of PowerTOST by FDA? It would provide me an additional argument for using PowerTOST for formal sample size estimation in our company.

Maybe this post helps.

About the validation of PowerTOST with examples:See this document1 about the acceptability of Base R. R is updated every couple of months with documented changes2 and maintaining a bug-tracking system.3 I recommend to use always the latest release.

The authors of PowerTOST tried to do their best to provide reliable and valid results. The package’s NEWS-file documents the development of the package, bug-fixes, and introduction of new methods. Issues are tracked at Git­Hub (as of today none is still open). So far the package had ≈93,000 downloads. Therefore, it is extremely unlikely that bugs were not detected given its large user base.

However, the ultimate responsibility of validating any software (yes, of SAS as well…) lies in the hands of the user.
• The software programs […] should be suitable and validated for the intended use. Whether standard, off-the-shelf software is purchased or bespoke software is developed, developer, vendor and/or service provider qualification and/or validation certificates may be provided but it is the user’s responsibility to ensure that the software is validated for its intended use and that it was developed in a controlled manner in accordance with a QA system. […] There should be SOPs in place for usage of each software program that is used to perform activities of a BE study. […] Software programs used […] should be specified in writing. […] These requirements apply to all systems used in clinical BE studies, e.g. […] for statistical analysis […].4
• The credibility of the numerical results of the analysis depends on the quality and validity of the methods and software (both internally and externally written) used […] for processing the data statistically. Data management activities should therefore be based on thorough and effective standard operating procedures. The computer software used for […] statistical analysis should be reliable, and documentation of appropriate software testing procedures should be available.5
• FDA does not require use of any specific software for statistical analyses […]. However, the software package(s) used for statistical analyses should be fully documented in the submission, including version and build identification.6

1. The R Foundation for Statistical Computing. A Guidance Document for the Use of R in Regulated Clinical Trial Environments. Vienna. October 18, 2021. Online.
2. The R Foundation. R News. 2022-04-22. Online.
3. Bugzilla. R bug tracking system. Online.
4. WHO. Guidance for organizations performing in vivo bioequivalence studies. Geneva. May 2016. Technical Report Series No. 996, Annex 9. Section 4.4. Online.
5. FDA, CDER/CBER. E9 Statistical Principles for Clinical Trials. Rockville. September 1998. Section V.H. Download.

Dif-tor heh smusma 🖖🏼 Довге життя Україна!
Helmut Schütz

The quality of responses received is directly proportional to the quality of the question asked. 🚮
Science Quotes