Protecting the Study Blind in IRT Processing

In recent years there has been an upsurge in professional vigilance with regard to maintaining the study blind in clinical trials. Concern about incidental unblinding — i.e., an unblinding or ‘partial unblinding’ that occurs accidentally in the course of modifying some other aspect of a trial– has grown in proportion to new strategies and techniques adopted by the industry. These concerns apply to all sectors of a study strategy, including outsourced players like IRT (IWR/IVR) systems. Veracity Logic founder Steve Zimmerman led a panel of colleagues in discussion of this subject at the CBI IRT conference in Philadelphia in 2015.

Here’s one example of a partial unblinding that can derive from IRT processing:  Your shipping schedule is set up to automatically resupply a study site when  certain parameters are met.  When the difference between the target (Baseline) inventory and the trigger inventory (Alert Level) is less than 2, systems will generate a shipment each time a kit is assigned to a subject. If the newly shipped kit is assigned to a different subject, investigators will rightly conclude that the subjects are on the same treatment — they won’t know which treatment, just that it’s the same for the two subjects. Such a perception can lead to bias in treating them. This kind of weakening of the blind is easily avoided by having your IRT appropriately configured.

Adaptive randomization designs provide a good warning of the kind of complete incidental unblinding that can derive from IRT processing if not planned properly by experienced professionals at the outset. Adaptive designs may allow the shutdown of certain treatment groups during the trial, modification of cohort sizes,  or other forms of  parameter modification based on interim study results. Making sure these occur in ways that protect the blind is a key requirement for good design of IRT systems.

An article by Leon Wyszkowski, Steven Yoder, and Susan Diehl in Applied Clinical Trials (Dec. 14, 2015)  sums up the important role of  a well-executed IRT in ensuring the validity of study results: “Interactive response technology…usually plays a large role in designing and controlling adaptive trials so that randomization, the supply chain, and blinding strategy remain robust and protected. Preparing an adaptive design without adequate technology is not recommended, especially in larger trials.”

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