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.