Risk Categorization Comparisons Between Different Cholesterol Measures

Background/Purpose: Few studies have been conducted that make comparisons between traditional measures of cholesterol (LDL, HDL, triglycerides, non-HDL, total cholesterol) and the emerging risk factors of cholesterol subfractions.  Additionally, few studies has compared LDL particle number, LDL particle size, and traditional measures among End-Stage Renal Disease (ESRD) patients. Therefore, the purpose of this study was to examine the relationships and differences in risk stratification of traditional measures when using National Cholesterol Educational Program guidelines compared to cholesterol particle number and size.   Methods: ESRD patients (N=1092) from clinics associated with the Central Texas Nephrology Associates were recruited to participate in this cross-sectional study.  Analysis/Results: LDL particle size categorized more patients at-risk when compared to LDL-C, non-HDL-C, HDL, and triglycerides.  Pearson correlation coefficients revealed a strong significant correlation between LDL cholesterol and LDL particle number (r²=.908, p=.0001) and a weak, inverse but significant correlation between LDL particle number and LDL particle size (r²=-.290, p =.0001).  A significant but weak correlation existed between LDL-C and LDL particle size (r²= .107, p=.0001).  A significant correlation existed between LDL particle number and triglycerides (r²=.335, p=.0001) and a significant inverse correlation between LDL particle size and triglycerides (r²= -.500, p=.0001).  Conclusions: LDL particles are a significant part of cholesterol transport that has downstream effects of entering the artery wall, becoming modified through oxidation, and are engulfed by macrophages to substantially increase plaque accumulation and calcification by the creation of foam cells.  A greater question that must be ascertained from research with ESRD patients is whether LDL particle size is simply a marker for CHD that is reflective of increased risk that is no greater than LDL-C, non-HDL-C or triglycerides and if LDL particle size has a direct causative effect that directly promotes atherosclerotic plaque accumulation that is independent.  Small LDL particles may simply be a reflection of increased triglyceride levels and low HDL-C which is common in ESRD patients.  Our study seems to suggest that at the very least using LDL particle size may help to identify those who would not be considered at-risk using LDL-C, non-HDL-C, LDL-P or triglycerides alone and can possibly be used as a further screening measure.  Small LDL particles may play a more important role in those with ESRD as a means of primary prevention rather than an apparently healthy population.