The Journal of Prevention of Alzheimer’s Disease, 2019


Duplicate and deceptive subjects, a significant issue in CNS studies, are not often considered in Alzheimer’s Disease (AD) clinical trials. However, AD patients and their study partners may be motivated to take advantage of different  mechanisms of action, increase odds of receiving active treatment, and/or obtain financial compensation, which may lead them to participate in multiple studies. CTSdatabase reviewed memory loss subjects (n=1087) from January 2017 through May 2019 to determine how many attempted to screen at multiple sites. 117 subjects (10.8%) visited more than one site within two years. When these potential AD subjects went to additional sites, it was predominantly for non-memory indications (often MDD or schizophrenia). For those that participated in studies, the rate of duplication approached 4% of screened AD subjects. This data indicates that significant numbers of AD subjects attempt to enroll at multiple sites, which confounds efficacy and safety signals in clinical trials.

Keywords: Professional research subject, deception, duplicate subjects, dual enrollment

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Introduces research suggesting that the subjects entered into the latter part of Phase 3 studies are more likely inappropriate (duplicate/professional) than in Phase 2 and Early Phase 3 studies.

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The Journal of Clinical Pharmacology, 2016


Accounting for subject nonadherence and eliminating inappropriate subjects in clinical trials are critical elements of a successful study. Nonadherence can increase variance, lower study power, and reduce the magnitude of treatment effects. Inappropriate subjects (including those who do not have the illness under study, fail to report exclusionary conditions, falsely report medication adherence, or participate in concurrent trials) confound safety and efficacy signals. This paper, a product of the International Society for CNS Clinical Trial Methodology (ISCTM) Working Group on Nonadherence in Clinical Trials, explores and models nonadherence in clinical trials and puts forth specific recommendations to identify and mitigate its negative effects. These include statistical analyses of nonadherence data, novel protocol design, and the use of biomarkers, subject registries, and/or medication adherence technologies.

Keywords: Nonadherence, professional subjects, duplicate subjects, adherence, clinical trials.

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Innovations in Clinical Neuroscience, 2013


Objective: To report the results of the first 1,132 subjects in a pilot project where local central nervous system trial sites collaborated in the use of a subject database to identify potential duplicate subjects.

Method: Central nervous system sites in Los Angeles and Orange County, California, were contacted by the lead author to seek participation in the project. CTSdatabase, a central nervous system-focused trial subject registry, was utilized to track potential subjects at pre-screen. Subjects signed an institutional review board-approved authorization prior to participation, and site staff entered their identifiers by accessing a website. Sites were prompted to communicate with each other or with the database administrator when a match occurred between a newly entered subject and a subject already in the database.

Results: Between October 30, 2011, and August 31, 2012, 1,132 subjects were entered at nine central nervous system sites. Subjects continue to be entered, and more sites are anticipated to begin participation by the time of publication. Initially, there were concerns at a few sites over patient acceptance, financial implications, and/or legal and privacy issues, but these were eventually overcome. Patient acceptance was estimated to be above 95 percent. Duplicate Subjects (those that matched several key identifiers with subjects at different sites) made up 7.78 percent of the sample and Certain Duplicates (matching identifiers with a greater than 1 in 10 million likelihood of occurring by chance in the general population) accounted for 3.45 percent of pre-screens entered into the database. Many of these certain duplicates were not consented for studies because of the information provided by the registry.

Conclusion: The use of a clinical trial subject registry and cooperation between central nervous system trial sites can reduce the number of duplicate and professional subjects entering clinical trials. To be fully effective, a trial subject database could be integrated into protocols across pharmaceutical companies, thereby mandating site participation and increasing the likelihood that duplicate subjects will be removed before they enter (and negatively affect) clinical trials.

Keywords: Duplicate subjects, professional subjects, professional patients, site cooperation, investigator collaboration, subject database, subject registry

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