The Diversity of Research Participants in Randomized Controlled Trials and Observational Studies Conducted by the...

Rationale: Women, older individuals, and racial and ethnic minority groups are often underrepresented in research studies. Objectives: We evaluated the demographics and diversity of participants enrolled in randomized controlled trials (RCTs) and observational studies published by investigators in association with the Canadian Critical Care Trials Group. Methods: We performed quantitative content analysis of peer-reviewed RCTs and observational studies from December 1994 to December 2022. For each publication, we extracted participant demographic variables, including sex, gender, age, race or ethnicity, sexual orientation, pregnancy status, language proficiency, income/financial status, housing, education, disability, and geography. Results: A total of 120 publications (28 RCTs, 92 observational studies) included 211,144 enrolled participants. Most (107 of 120; 89.2%) were multicenter studies, and 70% (84 of 120) were conducted exclusively in Canadian centers; 77.5% (93 of 120) studies enrolled adult participants, and 19.2% (23 of 120) enrolled pediatric participants. All studies reported participant mean or median age, 118 (98.3%) reported binary sex or gender, and 9 (7.5%) reported race or ethnicity. No justification was provided in 35 studies that listed pregnancy as an exclusion. There was infrequent reporting of housing (n = 4), employment (n = 2), income (n = 2), and education (n = 1). No studies reported the language proficiency, sexual orientation, disability, or geography of participants. Of the studies reporting gender, women and/or girls comprised 42.3% participants (range, 8.9-67.7%). Within nine studies reporting race or ethnicity of 2,950 participants, 59.7% were White, 8% South Asian, 7% Indigenous, 3% Asian, 1% Black, 14% unknown, and 6% "other." Conclusions: Research publications from the Canadian Critical Care Trials Group infrequently report important participant demographics, and diversity of research participants is disproportionate compared with Canadian societal demographics.