Race/ethnicity reporting and representation in US clinical trials: A cohort study

Summary: Background: Systemic progress in improving trial representation is uncertain, and previous analyses of minority trial participation have been limited to small cohorts with limited exploration of driving factors. Methods: We analyzed detailed trial records from all US clinical trials registered in ClinicalTrials.gov from March 2000 to March 2020. Minority enrollment was compared to 2010 US Census demographic estimates using Wilcoxon test. We utilized logistic regression and generalized linear regression with a logit link to assess the association of possible drivers (including trials' funding source, size, phase, and design) with trials' disclosure of and amount of minority enrollment, respectively. Findings: Among 20,692 US-based trials with reported results (representing ~4?76 million enrollees), only 43% (8,871/20,692) reported any race/ethnicity data. The majority of enrollees were White (median 79?7%; interquartile range [IQR] 61?9-90?0%), followed by Black (10?0%; IQR 2?5-23?5%), Hispanic/Latino (6?0%; IQR 0?43-15?4%), Asian (1?0%; IQR 0?0-4?1%), and American Indian (?0%; IQR 0?0-0?2%). Median combined enrollment of minority race/ethnicity groups (Black, Hispanic/Latino, Asian, American Indian, Other/Multi) was below census estimates (27?6%) (p