Clinical trial exclusion criteria have increased nearly 60% over the past three decades, according to a recently published study. The steadily increasing exclusion criteria may decrease the likelihood of successful trial completion and generalization of results according to researchers. The study, which was recently published in the Journal of Thoracic Oncology, includes an examination of 74 National Cancer Institute-sponsored lung cancer trials from 1986-2016. The researchers spoke with Outsourcing-pharma.com about their findings.
Explaining the increasing complexity and volume of exclusion criteria
Isolating a single culprit is difficult, as with any investigation. Dr. David Gerber admits that there are likely several reasons behind exclusion criteria growth. One possible reason, Gerber explains, is that treatment regimens have become more complicated, raising new safety concerns for some treatments. Study populations are now more precisely defined by molecular features in addition to cancer anatomic site and histology. Additionally, Gerber explains that it appears as though “some clinical trial protocols carry forward eligibility criteria from earlier studies of older treatments, even if those criteria are no longer directly relevant to the current clinical trial… for these and other reasons, eligibility criteria have increased in complexity and number.”1
Hindering clinical research
How is the trend of increasing complexity and volume of exclusion criteria potentially impeding clinical research? For starters, the increase may could prolong the screening process and increase the likelihood of protocol misunderstanding. Furthermore, Gerber suggests that increases in eligibility criteria can decrease the number of eligible patients, prolong study duration, decrease the likelihood of completion, and decrease generalizability of trial data.
The study examined lung cancer clinical trials, but this is not an isolated occurrence. Gerber adds that increases in eligibility criteria have also been reported in breast, gastrointestinal, and gynecologic cancers, and other malignancies including non-cancer fields.1
What can be done to mitigate this issue? Geber advises that “if a criterion is not truly needed to protect patient safety or to preserve the scientific integrity of the study, then consideration should be given to eliminating or relaxing it.”1
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