Under-reporting and under-representation of non-Hispanic Black subjects in lipid-lowering atherosclerotic cardiovascular disease outcomes trials: A systematic review

Published:August 30, 2022DOI:


      • Black subjects are under-reported in lipid-lowering ASCVD outcomes trials.
      • Black subjects are under-represented in lipid-lowering ASCVD outcomes trials.
      • Inclusion of Black persons will help to address disparities in preventive care.



      Non-Hispanic (NH) Black participants have been under-represented in studies of cardiovascular disease.


      We sought to determine the trends of reporting and representation of NH Black subjects in randomized controlled trials (RCTs) of lipid-lowering therapies demonstrating atherosclerotic cardiovascular disease (ASCVD) risk reduction benefit.


      The electronic databases of MEDLINE, EMBASE and were searched from 1990-2020. Studies of lipid-lowering therapies (i.e., statins, ezetimibe, proprotein convertase subtilisin/kexin type 9 inhibitors [PCSK9], and icosapent ethyl) with proven ASCVD benefit, sample sizes of at least 1000 subjects and follow-up of at least 1 year were included (40 RCTs, N=306 747 total participants). We examined articles and supplementary material for participant-level race data. Using United States disease prevalence data, the participation-to-prevalence ratio (PPR) metric was used to estimate the representation of NH Black subjects compared with their reported disease burden (i.e., < 0.8 indicated under-representation; > 1.2, over-representation; and 0.8 to <1.2, adequate representation).


      The median (interquartile range) number of participants per trial was 4871 (2434-10077). NH Black enrollees comprised 7.3% (95% CI, 0.9%-15.4%) of the total number of subjects reported. During the time intervals 1990-1995, 1996-2000, 2001-2005, 2006-2010, 2011-2015 and 2016-2020, NH Black participation was 0%, 1.1%, 4.4%, 4.8%, 0.2% and 0.7% respectively (P for trend <0.001). For statin trials, the participation of NH Black subjects was reported in 0 studies between 1990-1995 and in 9 of 28 trials from 1996-2020. For ezetimibe and icosapent ethyl, NH Black participants were reported in 0 of 3 and 0 of 1 studies, respectively. For trials of PCSK9 inhibitors, NH Black subjects were reported in 2 of 5 (40%). NH Black participants were under-represented compared with their disease burden in studies evaluating subjects with diabetes, hypercholesterolemia, stable coronary artery disease, and acute coronary syndrome (PPR < 0.8 for all).


      NH Black participants are markedly under-represented, and results are under-reported. The inclusion of population and disease specific representation of NH Black persons and their related social determinants of health will help to address the disparity in preventive care for this historically undertreated population.

      Graphical abstract



      RCTs (Randomized controlled trials), NH (Non-Hispanic), LDL-C (Low density lipoprotein-cholesterol), PPR (Participation-to-prevalence ratio), ASCVD (Atherosclerotic cardiovascular disease), ACS (Acute Coronary Syndrome)
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