You May Have Worked on More Adaptive Designs Than You Think

According to clinicaltrials.gov (accessed March 29, 2014), there are over 1500 open clinical trials in the field of stroke. During the design of a clinical trial, a number of important design decisions must be made. Although study success depends on their accuracy, there may be limited information to guide the decisions. Adaptive designs address this uncertainty by allowing a review of accumulating data during an ongoing trial, and modifying trial characteristics accordingly if the interim information suggests that some of the original decisions may not be valid. Correspondingly, adaptive designs have received a great deal of recent attention in the statistical, pharmaceutical, and regulatory fields. However, it is well known that implementing many of the proposed adaptations will require the clinical trials community to address a number of statistical, logistical, and operational hurdles1, 2. For that reason, although some recent stroke trials have utilized adaptive methods, it may appear upon first glance that adaptive designs are not being widely utilized. Yet, nearly all current stroke trials utilize group sequential methodology (interim monitoring) to some extent. Many researchers might think that these group sequential methods are a separate concept from adaptive designs. However, there is a close connection between the two. I give a brief description of each of these methods, and explain how these two statistical approaches are related.