Race and Ethnic Representation in Crohn's Disease Trials of Biologic and Small Molecule Medications: A Systematic Review and Meta-analysis

Background and aims: Randomised controlled trials historically under-represent marginalised racial and ethnic populations. As incidence and prevalence of Crohn's disease in these groups rise, it is important to characterise their inclusion in randomised controlled trials on first-line and pipe-line medications.

Methods: PubMed was searched systematically for randomised controlled trials of biologic and small molecule inhibitor [SMI] medications, with a primary outcome related to efficacy following PRISMA guidelines. We used descriptive statistics to summarise demographic variables and meta-regression analyses to estimate temporal trends in racial inclusion.

Results: More than a half of trials did not report any racial/ethnic demographics [53.7%] and several reported racial demographics for only one race [20.9%]. When racial data were reported, Whites made up 90.2% of participants. Percentages of Black, Asian, Native American/Pacific Islander, and participants considered 'Other' averaged 2.9%, 11.6%, 0.5%, and 1.6% out of the total sample sizes of 3901, 3742, 828 and 4027, respectively. Proportional representation of White participants decreased over time [p <0.01] and proportional representation of Asian participants increased over time [p = 0.047]. In ordinal logistic regression, mean year of trial enrolment significantly increased the number of racial groups reported [p <0.001].

Conclusions: Half of published randomised controlled trials in Crohn's disease contain no racial or ethnic demographics, and the remaining often only have limited inclusion of Black, Native American/Pacific Islander, and Hispanic patients. Further work should characterise representation in observational and prospective trials. Researchers should work to: 1] increase reporting of racial and ethnic demographics; and 2] improve recruitment and retention of marginalised populations.