P215: From Exclusion to Inclusion, a 10-year Analysis of Language Barriers in Clinical Trial Diversity - An IRB Perspective
Poster Presenter
Viviana Coppo
IRB Principal Chair
WCG United States
Objectives
Equitable representation in clinical research is undermined by language based eligibility criteria. This analysis examines trends in English fluency requirements and their impact on inclusion, highlighting ethical and regulatory concerns from an IRB perspective.
Method
We analyzed 101,439 ClinicalTrials.gov studies (2014–2024) using a Python based extraction of language eligibility criteria. Analyses assessed trends, compared protocols with public summaries, and stratified results by sponsor and study design.
Results
Applying the study’s three step analytic framework, we observed distinct temporal and structural patterns in language based eligibility criteria across 101,439 interventional studies. Longitudinal analyses showed that references to comprehension based requirements remained relatively stable, whereas explicit English fluency requirements increased markedly—by 65.5% in public study summaries and by more than 200% in studies with available full protocols. Comparative assessment of 26,483 protocol documents and corresponding registry summaries revealed that full protocols consistently contained more restrictive language criteria, indicating that substantial exclusionary elements are not captured in publicly available abstracts. Stratification by sponsor type and study design further demonstrated significant variation in the use of exclusionary language, with behavioral and observational studies showing the highest prevalence (77.67%), followed by device and drug trials. These results were interpreted using the Linguistic Determinants Pyramid, which contextualizes the progression from basic literacy to the advanced, domain specific proficiency implicitly required for participation in many clinical trials.
Conclusion
Equitable representation in clinical research may be compromised by exclusionary language based eligibility criteria. In the United States, approximately 22% of individuals speak a language other than English at home, and an estimated 88% of adults demonstrate limited health literacy. Health literacy is closely linked to linguistic proficiency; even native English speakers may experience functional limited English proficiency (LEP) when confronted with specialized medical terminology and complex informed consent documents. Consequently, eligibility criteria based on language fluency—rather than demonstrable comprehension—violate the principles of the Belmont Report and contradict federal mandates requiring understandable informed consent and equitable subject selection.
Consistent with these concerns, the present findings indicate that language fluency—typically defined as the ability to speak, read, or write in English—is increasingly used as an eligibility criterion in clinical research. Such practices shift the burden of understanding from study design to participants, including responsibility for navigating linguistically complex and high reading level materials.
Achieving scientifically robust and generalizable outcomes requires sponsors to invest in professional translation and interpretation services and for Institutional Review Boards to rigorously evaluate and justify language based exclusions. Moving away from language fluency and literacy proxies toward flexible, accessible consent processes is essential to ensuring that study populations reflect target demographics and that clinical research remains ethically sound and scientifically valid. Future work should evaluate IRB review practices and examine the impact of accessible consent strategies on enrollment equity.
