Race and ethnic representation among clinical trials for diabetic retinopathy and diabetic macular edema within the United States: A review

Purpose: Evaluate racial and ethnic representation in clinical trials compared to the disease burden for diabetic retinopathy (DR) and diabetic macular edema (DME) within the United States (US). Diabetic retinopathy (DR) is currently the leading cause of blindness in American adults, affecting over 7.7 million individuals and disproportionately affecting Black Americans. Black patients represent 38.3 ± 16.5% of DME within the US population while White patients represented 44.6 ± 18.3% of the DME population in the US. Methods: All completed interventional clinical trials involving the conditions “Macular Edema” or “Diabetic Retinopathy” between 2001 and 2020. Excluded studies had fewer than 50 participants, terminated early, did not have published results, or involved locations outside the US. Results: Twenty-five clinical trials were included in this review. In National Institute of Health (NIH) and industry-sponsored clinical trials for DME, the proportion of Black patients was 12.6 ± 3.3% (p < 0.05) and 8.6 ± 2.9% (p < 0.05), respectively. White patients’ representation in NIH and industry-sponsored trials was significantly greater at 69.5 ± 4.4% (p < 0.05) and 80.0 ± 2.2% (p < 0.05), respectively. For DR trials, the proportion of Black patients in NIH and industry was 23.3 ± 11.7% and 11.2 ± 2.2%, respectively. Conclusions: Black patients are under-represented by a 3.0-fold disparity in NIH trials and 4.5-fold disparity in industry trials for DME, while White patients are overrepresented. In industry-funded DR trials, there is a 2.1-fold disparity compared to disease burden. Clinical trials for diabetic eye disease should aim to recruit patients based on the disease burden, which enables measurements of treatment outcomes by race and promotes health equity.