Lipoprotein(a), Insulin Resistance, and Cardiovascular Disease in the UK Biobank

Background Insulin resistance (IR) and lipoprotein(a), Lp(a), are established contributors to cardiovascular disease (CVD) risk. Whether IR modifies the association between Lp(a) and CVD in primary prevention remains uncertain. Methods This prospective cohort study included UK Biobank participants without baseline CVD. IR at enrollment was assessed using the triglyceride‐glucose index (TyG). The primary outcome was first major adverse cardiovascular event, defined as peripheral arterial disease, coronary artery disease, myocardial infarction, ischemic stroke, or cardiovascular death. Cox models estimated adjusted hazard ratios (aHRs) with 95% CIs for log‐transformed Lp(a) and TyG, adjusting for each other. Lp(a) was categorized as <125 or ≥125 nmol/L; high IR was TyG ≥75th cohort percentile. Participants were stratified into 4 joint Lp(a)/IR groups using low Lp(a)/low IR as reference. Results Among 328 031 participants (mean age 56.4 years; 54.7% women), 26 865 CVD events occurred over 14.6 years median follow‐up (interquartile range 13.7–15.4). Per 1‐SD increase, aHRs were 1.08 (95% CI, 1.06–1.09) for log‐Lp(a) and 1.06 (95% CI, 1.04–1.07) for TyG, each adjusted for the other. The P ‐value for the multiplicative interaction between TyG and Lp(a) was 0.07. Relative to reference, aHRs (95% CI) were 1.15 (1.10–1.20) for ≥125/low IR, 1.09 (1.06–1.12) for <125/high IR, and 1.32 (1.24–1.41) for ≥125/high IR. Conclusions Lp(a) and IR each independently contribute to cardiovascular risk, with a combination offering improved risk stratification. This suggests that accounting for IR may enhance the assessment of Lp(a)‐associated risk in the context of primary CVD prevention setting.