Features
Who’s In and Who’s Out?
Finding the balance in clinical trial eligibility between too strict, not strict enough,
and “just right”
To assess a drug or device’s safety and efficacy, researchers and regulators often rely
on randomized, controlled clinical trials.
And, to ensure that those trials provide reproducible, valuable results with minimal
risk to the trial participants, investigators
designing the protocols incorporate strict
inclusion and exclusion criteria. Many
have called into question whether those
criteria are too strict, and if the populations enrolled in randomized clinical
trials accurately reflect their real-world
counterparts.
“Investigators imagine a question
and apply it to a very focused patient
population that they believe has the
greatest chance of showing an effect
size and the least chance of having any
complication or harm from the intervention,” Robert Fowler, MD, MS, a
senior scientist at Sunnybrook Health
Sciences Centre in Toronto, explained to
ASH Clinical News. “Often that means
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ASH Clinical News
that investigators end up excluding large
groups of the general patient population
who might be potentially eligible for a
clinical trial.”
When designing clinical trials, it can
be difficult to balance internal validity
(whether a treatment will work within the
defined study population) with external
validity (whether the results of a trial can
be generalized to other populations or settings). “The challenge and tradeoff is that
the generalizability of the trial oft