Clinical trial exclusion criteria growing in complexity and number

By Melissa Fassbender

- Last updated on GMT

Exclusion or eligibility criteria determine if a patient can participate in a clinical trial. (Image: iStock/hxdbzxy)
Exclusion or eligibility criteria determine if a patient can participate in a clinical trial. (Image: iStock/hxdbzxy)

Related tags Cancer Clinical research Clinical trial

Clinical trial exclusion criteria has increased nearly 60% over the last 30 years – and may decrease the likelihood of successful trial completion and generalizability of results, say researchers.

The researchers examined 74 National Cancer Institute-sponsored lung cancer trials from 1986 to 2016 and found a nearly 60% increase in exclusion or eligibility criteria.

The research was recently published​ in the Journal of Thoracic Oncology.

Why have exclusion criteria increased in complexity and number?

There are likely several reasons​,” Dr. David Gerber, associate professor of Internal Medicine and of Clinical Sciences and associate director for clinical research in the Harold C. Simmons Comprehensive Cancer Center told

Increases in the median number of exclusion criteria for lung cancer studies:

16 from 1986-1995

19 from 1996-2005

27 from 2006-2016

Gerber explained that treatment regimens have become more complicated and new safety concerns have emerged for some treatments. Study populations are also being defined more precisely, “not just by cancer anatomic site and histology but also by molecular features​,” he said.

Additionally, it appears that 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​,” added Gerber. “For these and other reasons, eligibility criteria have increased in complexity and number​.”

Impeding clinical research

Gerber explained increases in eligibility criteria complexity and number may prolong the screening process and increase the potential for protocol misunderstanding, which can lead to potential protocol deviations or violations.

Additionally, increases in eligibility criteria can decrease the number of eligible patients, and subsequently, can prolong study duration and decrease the likelihood of study completion. Importantly, Gerber added, it can also decrease the generalizability of study results.

To mitigate these challenges, Gerber suggested that those involved in clinical trials design—including researchers, sponsors, and regulatory authorities—could examine every eligibility criteria critically.

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​,” he said.

While the research reviewed lung cancer trials, the increase in exclusion criteria is not specific to lung cancer.

Increases in eligibility criteria have also been reported in breast, gastrointestinal, and gynecologic cancers, as well as other malignancies​,” explained Gerber – and it has been noted in non-cancer fields as well, he added.

This is a critical issue that clinical researchers in many fields are facing​,” said Gerber. “I am hopeful that current efforts to evaluate this issue may result in clinical trials that are more practical and feasible​.”

Source: Journal of Thoracic Oncology
DOI: 10.1016/j.jtho.2017.07.020
Thoracic oncology clinical trial eligibility criteria and requirements continue to increase in number and complexity
Authors: Garcia S, Bisen A, Yan J, Xie X-J, Ramalingam S, Schiller JH, Johnson DH, Gerber DE

Related topics Clinical Development

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