PROJECT SUMMARY
Clinical studies are often conducted under idealized and rigorously controlled conditions to improve their
internal validity and success rates, but compromise their external validity (i.e., generalizability to the target
populations). These idealized conditions are sometimes exaggerated and reflected as overly restrictive
eligibility criteria. Certain population subgroups are often excluded with unjustified criteria and are
subsequently underrepresented. Older adults have been especially underrepresented in cancer studies. The
underrepresentation of these population subgroups reduces the treatment effects and increases the likelihood
of adverse outcomes in diverse populations when the interventions were moved into clinical practice. It is
imperative to rigorously assess the generalizability of a clinical study, so that stakeholders including
pharmaceutical companies, policymakers, providers, and patients would be able to understand and anticipate
the possible effects of the interventions in the real world. In the past two decades, a large number of studies
have assessed generalizability, but mostly were after the fact, ad hoc, not systematic, and focused on specific
diseases and sets of trials without a formalized approach. So far, there is a significant knowledge gap between
the available methods for generalizability assessment and their adoption in research practice. Most
generalizability assessments have been conducted as an ad hoc auditing effort by a third party after the fact.
We believe the key barriers are two-fold: (1) the lack of evidence to demonstrate their validity, which also leads
to the lack of consensus on the best practice for generalizability assessments; and (2) the lack of readily
available, well-vetted statistical and informatics tools. Motivated to fill this gap, we propose to first
systematically review the extant methods for generalizability assessments, and then use a data-driven strategy
to reproduce, evaluate, and compare these methods with our unique data resource, the OneFlorida Data, one
of the 13 PCORI-funded Clinical Data Research Networks that contains linked EHRs, claims, and cancer
registry data for ~15 million Floridians. We will develop an open-source generalizability assessment software
toolbox and its accompanying documentations and tutorials. The success of this R21 project will (1) fill a
knowledge gap on the validity and utility of the different generalizability assessment methods; (2) provide an
easy-to-use toolbox ctGATE for assessing study generalizability much-needed by the clinical research
community; (3) help the clinical researchers choose the most appropriate generalizability assessment methods
with readily available implementations; and (4) build a body of evidence to support the development of an
eligibility criteria design tool for optimizing study generalizability at the study design phase.