A comprehensive analysis of clinical trials conducted by DRCRnet has uncovered significant racial and ethnic disparities in diabetic macular edema (DME) research participation and disease severity. The study, published in the American Journal of Ophthalmology, examined data from 17 clinical trials conducted between 2003 and 2020.
Representation Gap in Clinical Trials
The analysis revealed a stark contrast between trial participation and US demographics. White participants were notably overrepresented at 75.8% compared to their 61.6% share of the US population according to the 2020 Census. While Black participants showed slight overrepresentation at 16.7% versus 12.4% in the general population, other minority groups were significantly underrepresented. Asian participation was merely 1.9% compared to their 6% population share, and Hispanic representation was 12.5% versus 18.7% in the general population.
Disease Burden and Clinical Characteristics
DME, affecting approximately 3.8% of US adults aged 40 and older, shows disproportionate impact across racial groups. Non-Hispanic Black patients account for 38% of DME cases despite representing only 16% of all diabetes cases. The study found distinct patterns in disease presentation and management across racial groups:
- Type 2 diabetes was more prevalent among Black (90.9%) and Asian (94.3%) participants compared to White (87.0%) and Hispanic (85.2%) participants
- Insulin use varied significantly, with lower rates among Asian (44.0%), Hispanic (55.5%), and other racial groups (56.8%) compared to Black (64.1%) and White (63.7%) participants
- Proliferative diabetic retinopathy showed higher prevalence in Asian (20%), Hispanic (22.9%), and other racial groups (27.1%) compared to White (18.7%) and Black (14.8%) participants
Clinical Outcomes and Risk Factors
The research identified several factors associated with worse visual acuity outcomes:
- Female gender
- Older age at diagnosis
- Hispanic ethnicity
- More severe diabetic retinopathy
The mean age of study participants was 61 years, with an average 17-year gap between diabetes diagnosis and trial enrollment. This extended duration potentially influences disease progression and treatment outcomes.
Study Limitations and Implications
The researchers noted several limitations, including the focus on government-funded DRCRnet trials, excluding industry-sponsored research. Additionally, the comparison of trial data spanning 2003-2020 with census data from only two time points may affect analytical accuracy.
Despite these limitations, the findings emphasize the critical need for more diverse recruitment in DME clinical trials. The underrepresentation of minority groups, coupled with their tendency to present with more severe disease, highlights a significant gap in clinical research that needs addressing to ensure more equitable and comprehensive treatment development.
