Sex and Ethnic Disparities in High-Density Lipoprotein Subclasses∗

Abstract

Synopsis: Several epidemiological studies have shown race and sex differences in conventional lipoprotein parameters. Descriptive studies on these differences in novel lipid subfractions, high-density lipoprotein (HDL) subclasses in particular, are very scant. Previous studies were performed only on biracial groups and in high-risk populations. Purpose: To determine the variances of the HDL subfractions in an ethnically diverse healthy adult population and to ascertain their impact on cardiovascular outcomes. Methods: Multi-Ethnic study of Atherosclerosis (MESA) is a population based study (n = 6814) of white (38%), black (28%), Chinese (22%), and Hispanic (12%) subjects, aged 45–84 years, with no self-reported cardiovascular disease. This is a post-hoc analysis of the NHLBI limited access dataset of MESA subjects who had data on lipid subclasses available (n = 6697). Individual lipoprotein subclasses were measured on frozen plasma specimens (−70 °C) using nuclear magnetic resonance spectroscopy. The end points analyzed were all-cause mortality, all CVD events and composite cardiovascular events. Chinese were arbitrarily selected as a reference cohort (lowest cardiovascular event rate). Multivariate analysis of variance was used to adjust for age, body mass index, hypertension, diabetes, any lipid-lowering medication and smoking. Results: Men had a greater incidence of cardiovascular events compared with women. Similarly, white subjects had more events compared with the other ethnic groups. The distribution of outcomes and the HDL subclasses across the various groups is detailed in the figure. Women had increased levels of HDL cholesterol and total HDL particles as well as significantly higher levels of large and medium HDL particles compared to men. Chinese subjects had greater levels of small HDL among all the racial groups. HDL size was greater among African-American subjects, and they had greater levels of large HDL compared with the other groups. Overall, interpretation of the HDL subclass distribution pattern reveals that the concentration of small HDL particles was inversely related to the number of cardiovascular outcomes across all the different ethnic groups. Conclusions: There were clear sex and race differences in HDL subclasses in this multiethnic cohort. These differences might provide a different atherogenic profile that is not apparent in a standard lipid panel. The current analysis might suggest a potential protective effect of small HDL on cardiovascular events.