Diabetic Macular Edema: Black Patients Benefit Less From Ranibizumab

Laird Harrison

October 09, 2021

Black patients get less visual acuity improvement than White patients when treated with ranibizumab for diabetic macular edema, according to the available data from clinical trials.

Ali Khan

The difference between the races disappears when the statistics are adjusted for such factors as HbA1c levels. But the findings raise questions that highlight the lack of data on ethnicity in clinical trials on retina treatments, said M. Ali Khan, MD, an assistant professor of ophthalmology at Thomas Jefferson University in Philadelphia.

"The ultimate message from the project is that we need to do a better job of recruiting patients from a variety of backgrounds," he told Medscape Medical News.

Khan presented his findings at the American Society of Retina Specialists (ASRS) 2021 Annual Meeting.

Few researchers have reported on differences among racial or ethnic groups in response to treatments for retinal conditions. "And obviously, with the George Floyd protests, I think people have been a little bit more interested in making sure that we are setting things correctly in in regard to diversity and inclusion," Khan said.

So, Khan and his colleagues examined data from Protocols I, S, and T from the Diabetic Retinopathy Clinical Research Network (DRCR) and the RISE and RIDE trials of ranibizumab funded by Genentech.

They counted a total of 928 White and 181 Black patients in the five trials. They found that White patients started at an observed mean best-corrected visual acuity (BCVA) of 62.0 ETDRS letters, which rose to 72.2 after 24 months, for an improvement from baseline of 10.0 letters. Black patients started with a mean of 66.7 letters, which rose to 72.8, an improvement of 7.8 letters. The difference in the letters of improvement was statistically significant (P = .04).

At the same time, 27.6% of Black patients and 35.0% of White patients had gains of at least 15 letters, which fell just short of statistical significance (P = .05).

The differences between the two races came from the RISE and RIDE data; differences in the other trials were not statistically different.

And these differences disappeared when the researchers matched the Black patients to White patients who had similar age, sex, HbA1c, central subfield thickness, and BCVA at baseline, and a similar number of ranibizumab injections and visits after 24 months.

The same held true when the patients were matched according to all these characteristics except HbA1c, and also when only the baseline characteristics were considered.

The researchers would have liked to include more factors, such as kidney function and socioeconomics in their analysis, but were limited to what had been gathered in these trials, Khan said.

By the same token, they were unable to analyze differences involving Asian, Latinx, and other ethnic and racial groups because these trials did not include enough patients from these groups.

It could be useful to subdivide some of these racial and ethnic groups, for example, by distinguishing between people with ancestry from different parts of Asia or Latin America, he said.

The under-representation of people of color is common to other medical specialties, Khan said. "It just means we have to do a better job of getting these patients enrolled in clinical trials, and how to do that is the harder question," he said.

Hiring more principal investigators of color might help, he said, adding that researchers should work to overcome any language barriers.

Abdul-Hadi Kaakour

Research in other medical specialties has identified socioeconomic factors and distrust of medical professionals as factors limiting the recruitment of under-represented groups, said Abdul-Hadi Kaakour, MD, MS, a fellow at Cleveland Clinic, in an email.

In a related study Kaakour presented at ASRS, he and his colleagues compared the representation of ethnical and racial groups in 15 randomized controlled trials for diabetic macular edema. They found that:

  • the White patient cohort was under-represented in two and overrepresented in 10

  • the Black patient cohort was under-represented in six and overrepresented in three

  • the Hispanic patient cohort was under-represented in nine and over-represented in three

  • the Asian patient cohort was under-represented in eight and overrepresented in three

  • the American Indian/Alaska Native and Hawaiian/Pacific Islander patient cohort was under-represented in four.

"Each person's barriers will be unique as well, so at the very least, spending extra time with patients who identify as under-represented minorities will allow the clinician to understand their particular barriers and find constructive ways to overcome them," Kaakour told Medscape Medical News.

Neither Kaakour nor Khan reported any relevant financial interests. Funding was provided by Genentech for the study presented by Khan.

American Society of Retina Specialists (ASRS) 2021 Annual Meeting. Presented October 9, 2021.

Laird Harrison writes about science, health and culture. His work has appeared in national magazines, in newspapers, on public radio and on websites. He is at work on a novel about alternate realities in physics. Harrison teaches writing at the Writers Grotto. Visit him at lairdharrison.com follow him on Twitter: @LairdH

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