Question special

Dear Drs. Trivedi, Shoptaw, and co-authors,
Thank you for all your work and dedication to the care of patients struggling with challenging addictions such as stimulant use disorder.

Reading the article, I was intrigued by the study design chosen by the authors for this clinical trial.

The authors chose a sequential parallel comparison design, conducting the trial in 2 stages, with rerandomization of the placebo group participants who did not have a response in the first stage. Such design necessitated the use of a randomization fraction and weight for every group, allowing for a weighted combination to analyze the response in each stage. The authors highlighted that the purpose of rerandomization was to enrich the sample in the second stage with participants who were unlikely to have a response to placebo.

Could you kindly share with us why this design, in particular, was chosen for this trial, what challenges did this design pose for the trial and how were they overcome? Could you shed more light on this study design for those of us who are not very familiar with this design?