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Minority Representation in Clinical Trials in the United States

Trends Over the Past 25 Years
      To The Editor:
      All members of society need to be represented in medical research, but there is major under-representation of racial and ethnic minorities in clinical trials.
      • Geller S.E.
      • Koch A.R.
      • Roesch P.
      • Filut A.
      • Hallgren E.
      • Carnes M.
      The more things change, the more they stay the same.
      The National Institutes of Health (NIH) Revitalization Act was created in 1993 to increase the inclusion of diverse populations in clinical research to decrease health care disparities.
      • Piantadosi S.
      Commentary regarding inclusion of women and minorities in clinical trials and the NIH Revitalization Act of 1993: the perspective of NIH Clinical Trialists.
      Even though the 2018 US Census Bureau population estimates report that non-Hispanic white Americans represent 60.7% of the US population, non-Hispanic whites of European ancestry comprise more than 90% of the population in clinical trials.
      US Census Bureau Quickfacts: United States 2018 [internet]. Washington, DC: Department of Commerce [cited August 20, 2019].
      This imbalance in clinical research inclusion leads to limitations in applying clinical data, therapeutic indexes, drug safety, and toxicity. Unsuccessful cancer therapies, as well as limitations in screenings owing to genetic variability, are other consequences.
      • Collins F.S.
      • Varmus H.
      A new initiative on precision medicine.
      Moreover, taking into account the financial consequences, LaVeist et al estimated that if the racial and ethnic health disparities gap had been closed during the 2003 to 2006 period, health care costs in the United States would have been decreased by $1.2 trillion.
      • Laveist T.A.
      • Gaskin D.
      • Richard P.
      Estimating the economic burden of racial health inequalities in the United States.
      The objective of this study was to determine the racial and ethnic minority representation in randomized clinical trials (RCTs) in the United States. Our original query on June 15, 2019, yielded 569,685 RCT publications, from which 254,535 (44.67%) were originating from the United States. A smaller proportion of 59,577 (23.41%) had NIH support, whereas the rest of the 194,958 (76.59%) were non–NIH-funded studies. The total percentage of minority inclusion from all RCTs published in the United States during the last 25 years was 3.95% (n=10,057); of those, 45.63% (n=4590) were from non–NIH-supported studies, and 54.36% (n=5467) were NIH-supported studies.
      The NIH-funded studies had a 4-fold increase in minority inclusion (an increment from 2.78% to 11.10%), compared with non–NIH-funded RCT studies, in which the total increase was 2.2-fold (from 1.23% to 2.78%) during the same period (Table).
      TableComparison of Ethnic/Racial Make-Up of Manuscripts Involving Minorities in 1993 and 2018
      All n=254,535Non-NIH n=194,958NIH n=59,577
      1993 (n=4439)2018 (n=7506)1993 (n=3648)2018 (n=5822)1993 (n=791)2018 (n=1684)
      All minorities1.51% (n=67)4.85% (n=364)1.23% (n=45)3.04% (n=177)2.78% (n=22)11.11% (n=187)
      Alaskan Native0% (n=0)0.05% (n=4)0% (n=0)0.02% (n=1)0% (n=0)0.18% (n=3)
      Asian American0.14% (n=6)1.04% (n=78)0.14% (n=5)1.1% (n=64)0.13% (n=1)0.83% (n=14)
      African American0.97% (n=43)2.23% (n=167)0.71% (n=26)1.13% (n=66)2.15% (n=17)6% (n=101)
      Pacific Islander0% (n=0)0.04% (n=3)0% (n=0)0.02% (n=1)0% (n=0)0.12% (n=2)
      Hispanic or Latino0.18% (n=8)1.24% (n=93)0.11% (n=4)0.5% (n=29)0.51% (n=4)3.8% (n=64)
      Native American0.09% (n=4)0.31% (n=23)0.08% (n=3)0.17% (n=10)0.13% (n=1)0.77% (n=13)
      Regarding specific minorities from all data, we found that the highest increase in inclusion was in African Americans: from 0.97% to 2.23%. The Hispanic/Latino representation rose in second place, from 0.18% to 1.24%, and Asian Americans rose from 0.14% to 1.04%. Inclusiveness of minorities in the United States for NIH-funded studies outpaced those without NIH funding (Figure).
      Figure thumbnail gr1
      Figure(Top) Time series graph showing the proportion of reported ethnic and racial minorities in randomized controlled trial (RCT) manuscripts (from journal titles, MEDLINE fields, and MeSH terms) without NIH support in PubMed, from 1993 to 2018. (Bottom) Time series graph showing the proportion of reported ethnic and racial minorities in RCT manuscripts (from journal titles, MEDLINE fields, and MeSH terms) with National Institutes of Health support in PubMed, from 1993 to 2018. Because a given publication may have included more than 1 minority group, the plot line representing “All minorities” will not necessarily equal 100%.
      These results support our hypothesis that although the NIH Revitalization Act of 1993 has helped stimulate the inclusion of traditionally under-represented populations in NIH-funded studies compared with those without NIH support; racial and ethnic minorities are still vastly under-represented in biomedical research.
      • Carey J.W.
      • Carnes N.
      • Schoua-Glusberg A.
      • et al.
      Barriers and facilitators for clinical care engagement among HIV-positive African American and Latino men who have sex with men.
      Our analysis shows that despite the NIH and its affiliated agencies’ best efforts to reduce the under-representation of minorities in RCTs, the current research environment is skewed toward studying the non-Hispanic white European population.
      • Bien S.A.
      • Wojcik G.L.
      • Hodonsky C.J.
      • et al.
      The future of genomic studies must be globally representative: perspectives from PAGE.
      As a result, health care disparities are aggravated within under-represented populations. Although the NIH guidelines have contributed to an increase in minority inclusion, continued efforts should be met to decrease the gap of health disparities, as, in the end, those who benefit from the development of new therapeutic interventions and treatments depend largely on who is studied.

      References

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        • Carnes M.
        The more things change, the more they stay the same.
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      1. US Census Bureau Quickfacts: United States 2018 [internet]. Washington, DC: Department of Commerce [cited August 20, 2019].
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        • Varmus H.
        A new initiative on precision medicine.
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        Barriers and facilitators for clinical care engagement among HIV-positive African American and Latino men who have sex with men.
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        • et al.
        The future of genomic studies must be globally representative: perspectives from PAGE.
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