Disparities persist in the inclusion of women, older adults, and racial and ethnic minorities in inflammatory bowel disease (IBD) clinical trials, according to study results published in Gastroenterology. Pregnant or lactating women were particularly underrepresented in ulcerative colitis (UC) studies.

In an analysis of US-based clinical trials conducted over the past 2 decades, the majority underenrolled older adults, Black patients, Asian patients, and Hispanic or Latino patients.

Investigators performed a cross-sectional analysis of all US-based clinical trials of IBD treatments as reported on ClinicalTrials.gov between 2000 and 2020. Participant age, sex, race and ethnicity, and pregnancy or lactation status were extracted from each study. Descriptive statistics were used to summarize the demographic information of trial participants. Overall, 146 studies were included in analyses. The pooled study cohort comprised 50,188 patients, among whom 25,899 (51.6%) were women. In trials specific to UC, however, the proportion of women was just 44.1%.

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Per census data, women are estimated to comprise approximately 55% of patients with IBD, suggesting significant underenrollment in UC-specific trials. Pregnant and/or lactating individuals were explicitly excluded from 64.6% of Crohn disease (CD)-specific trials and 59.4% of UC-specific trials. Of studies which did not cite pregnancy or lactation as exclusion criteria, none reported the proportion of patients who were pregnant or lactating.

All included studies reported cohort age distribution. Of studies specific to adults, the weighted mean age was 49.6 years. Patients aged 65 years and older were included in 39.1% of studies enrolling adults. Of these studies, patients aged over 65 years comprised less than 10% of the overall cohort. Just 1 study reported enrollment of adults aged 85 years and older. Incidence and prevalence of IBD is steadily increasing in older adults, with prior research reporting that 10% to 15% of patients are diagnosed after 60 years of age. Investigators highlighted the relatively small number of older enrollees as problematic, particularly given the aging population of patients with IBD.

Just 63 of 146 (43.2%) studied trials reported patient data by race. The pooled patient cohort of these 63 studies was 79.3% White. In CD-only trials, 90.2% of patients were White; in UC-only studies, 85.1% of patents were White. The proportion of enrolled Black patients ranged from 3% to 4.0%. Asian patients were similarly underrepresented, comprising just 7.6% of study populations with available race data. In trials with data available on ethnicity, just 4.1% of patients were classified as Hispanic or Latino.

Results from this literature review suggest critical gaps in IBD study enrollment. In particular, women, racial and ethnic minorities, and older adults were significantly underrepresented in trial rosters relative to their presence in the overall patient population. The lack of data on IBD intervention safety in pregnant and/or lactating individuals is another significant obstacle. Limitations of the present analysis include the lack of demographic data reported in certain studies and heterogeneity in included studies’ methodologies. Further research is necessary to better elucidate enrollment trends in the field of IBD research.

“Underrepresentation of specific demographic groups leaves gaps in our knowledge regarding drug and device efficacy and safety for a large population of patients with IBD,” investigators wrote. “Our findings suggest that investigators should focus on improving efforts to recruit underrepresented populations for clinical trials in IBD.”


Rabinowitz LG, Rabinowitz DG, Silver EM, Oxentenko AS, Williams KE, Silver JK. Disparities persist in inclusion of female, pregnant, lactating, and older individuals in inflammatory bowel disease clinical trials. Gastroenterology. Published online March 10, 2022. doi:10.1053/j.gastro.2022.03.016