Abstract 159: Sex Differences in the Association of Lipoprotein(a) with Subclinical Atherosclerosis in a South Asian Population

Abstract

Background: South Asians have high rates of cardiovascular disease (CVD) that are incompletely explained by traditional risk factors. Some studies have shown that South Asians have elevated levels of lipoprotein(a) [Lp(a)], an LDL-like particle that is a risk factor for CVD. We hypothesized that Lp(a) is associated with subclinical atherosclerosis in South Asians, independent of traditional risk factors. Methods: We used data from the Metabolic syndrome and Atherosclerosis in South Asians Living in America study, a community-based cohort (N=146; age 57 ± 8 years; 51% male) free of CVD. Serum Lp(a) was measured by immunonepholometric assay on a BNII nephelometer. Common carotid artery intima-media thickness (CIMT) was measured by ultrasonography. We used multivariate linear regression to test associations of Lp(a) with log-transformed CIMT after adjusting for age, sex, smoking, waist circumference, hypertension, cholesterol medications, C-reactive protein, and fasting insulin and glucose. In additional models, we further adjusted for traditional lipids: LDL- and HDL-cholesterol, and triglycerides. We tested for interactions by sex and stratified our analyses as appropriate. Results: Median Lp(a) levels were higher in women than men (0.18 vs. 0.13 g/L, respectively; p=0.06), and higher in post-menopausal vs. pre-menopausal women (0.20 vs. 0.12 g/L; p=0.007). However, median CIMT levels were lower in women compared to men (0.86 vs. 0.95 mm; p=0.002). There was an interaction (p=0.04) by sex in the relationship between Lp(a) and CIMT. In women, this relationship was significant (p=0.001), and it remained significant after further adjustment for lipid parameters (N=72, β coefficient 0.31, 95% CI 0.12 to 0.51; p=0.002). In contrast, there was no association in men between Lp(a) and CIMT in either model (p=0.66 and 0.32, respectively). In subgroup analysis, the association between Lp(a) and CIMT was stronger in post-menopausal women (N=52, β coefficient 0.35, 95% CI 0.08 to 0.62; p=0.01) and weaker in pre-menopausal women (p=0.62). Conclusions: Lp(a) was an independent predictor of subclinical atherosclerosis in South Asian women, but not in men. This differs from other populations, where associations tended to be stronger in men.