Participant Diversity in United States Randomized Controlled Trials of Antibacterials for Staphylococcus aureus Infections, 2000-2021.

Abstract

Equitable representation of members from historically marginalized groups is important in clinical trials, which inform standards of care. The goal of this study was to characterize the demographics and proportional subgroup reporting and representation of participants enrolled in randomized controlled trials (RCTs) of antibacterials used to treat Staphylococcus aureus infections. We examined randomized controlled registrational and strategy trials published from 2000-2021 to determine the sex, race, and ethnicity of participants. Participation to incidence ratios (PIRs) were calculated by dividing the percentage of study participants in each demographic group by the percentage of the disease population in each group. Underrepresentation was defined as a PIR <0.8. Of the 87 included studies, 82 (94.2%) reported participant sex; 69 (79.3%) reported participant race; and 20 (23.0%) included ethnicity data. Only 17 (19.5%) studies enrolled American Indian/Alaskan Native participants. Median PIRs indicated that Asian and Black participants were underrepresented in RCTs compared with the incidence of methicillin-resistant S. aureus (MRSA) infections in these subgroups. Underrepresentation of Black participants was associated with a larger study size, international sites, industry sponsorship, and Phase 2/3 trials compared with Phase 4 trials (P<0.05 for each). Black participants had over 4 times the odds of being underrepresented in Phase 2/3 trials compared with Phase 4 trials (OR 4.57; 95% CI 1.14-18.3). Standardized reporting methods for race and ethnicity and efforts to increase recruitment of marginalized groups would help ensure equity, rigor, and generalizability in RCTs of antibacterial agents and reduce health inequities.