Under-representation of ethnic and regional minorities in lipid-lowering randomized clinical trials: a systematic review and meta-analysis

Aims The efficacy of lipid-lowering therapies (LLT) amongst different ethnicities and regions remains unclear. We aimed to assess cardiovascular event reductions associated with LLT according to ethnicity and region in previously published randomized clinical trials (RCTs). Methods and results Medline, EMBASE, and Cochrane CENTRAL were searched for RCTs of statins, ezetimibe, or proprotein convertase subtilisin/kexin type 9 inhibitors comparing intensive vs. less-intensive low-density lipoprotein cholesterol (LDL-C) lowering. The primary endpoint was major adverse cardiovascular events (MACE) defined as the composite of cardiovascular mortality, myocardial infarction, stroke, and revascularization. Random-effects meta-analysis was used to pool risk ratios (RRs) with 95% confidence intervals (CI) adjusted per mmol/L reduction in LDL-C. Fifty-three trials with 329 897 participants were included. Amongst participants, 39.5% were from Europe, 16.0% from North America, 9.0% from Japan, 2.8% from Australasia, 1.8% from South America, 1.1% from Asia, 0.6% from South Africa, and 29.2% were unspecified. Amongst trials reporting ethnicities, there were 60.3% White, 20.2% Japanese, 9.4% Asian, 5.5% Black, and 4.7% Latin American. There was reduction in MACE with LLT in regions including Australasia (RR 0.75, 95% CI 0.67-0.85), North America (RR 0.75, 95% CI 0.69-0.83), Europe (RR 0.78, 95% CI 0.71-0.86), and Japan (RR 0.73, 95% CI 0.63-0.85) and in Black ethnicity (RR 0.55, 95% CI 0.37-0.82). Head-to-head comparisons between regions and ethnicities revealed no significant differences in MACE reduction. Conclusion Despite under-representation in clinical trials, regional and ethnic minority groups such as Australasia and Blacks appear to derive at least as much cardiovascular benefit from LLT. Lay Summary Lipid-lowering therapy (LLT) can effectively reduce cardiovascular disease across different ethnicities and regions, reinforcing the importance of their widespread use in at-risk populations.There is under-representation of several minority groups such as those from South Africa, South America, and Asia, as well as Black, Latin American, and Asian ethnicities. Furthermore, amongst included populations, the benefits of LLT appear to be consistent across regions and ethnicities.The findings of this study highlight the importance of ensuring at-risk patients have access to LLT regardless of ethnicity or region. Future trials should ensure adequate representation of all patient groups.