A systematic review of randomized controlled trials (RCTs) on antibiotics for Staphylococcus aureus infections found widespread underrepresentation of racial and ethnic minorities, researchers reported late last week in Clinical Infectious Diseases.
The study, led by researchers with Duke University School of Medicine and Yale School of Public Health, reviewed 87 RCTs of antibacterial drugs used to treat S aureus infections published from 2000 to 2021 to determine the race, sex, and ethnicity of participants. The researchers then calculated participation to incidence ratios (PIRs) by dividing the percentage of study participants in each group by the percentage of the disease population in each group. Under-representation was defined as a PIR of less than 0.8.
Of the 87 RCTs included, 82 (94.2%) reported participant sex, (69) 79.3% reported race, and 20 (23%) reported ethnicity data. Only 17 studies (19.5%) enrolled American Indian/Alaskan Native participants. While most RCTs had adequate or overrepresentation of female and White participants, median PIRs indicated that Asian (0.36) and Black (0.37) participants were under-represented compared with the incidence of methicillin-resistant S aureus (MRSA) infections in those subgroups.
Analysis of factors associated with underrepresentation of Black participants identified larger study size, international sites, industry sponsorship, and phase 2/3 trials compared with phase 4 trials as factors. Black participants were nearly five times less likely to be included in phase 2/3 trials compared with phase 4 trials (odds ratio, 4.57; 95% confidence interval, 1.14 to 18.3).
Increased enrollment of marginalized groups needed
The study authors say the level of underrepresentation of Black and other racial and ethnic subgroups they found "calls into question the generalizability of data used to evaluate the efficacy and effectiveness of antibacterial drugs for S. aureus infections," noting that Black populations experience higher rates of invasive MRSA infections compared with Whites. They say more effective strategies are needed to increase enrollment of marginalized groups.
"Our study reinforces the importance of enhancing strategies to optimize enrollment and reporting on diverse participants in RCTs of antibacterials used for S. aureus infections," they concluded.