Low-density lipoprotein (
LDL) cholesterol and
triglyceride-rich
lipoproteins constitute non-
high-density lipoprotein (non-
HDL) cholesterol. These are atherogenic
lipoproteins and non-
HDL cholesterol is a secondary target of treatment beyond
LDL cholesterol in patients with
hypertriglyceridemia. Some investigators favor total
apolipoprotein B over non-
HDL cholesterol as the secondary target of treatment. This is based on publications suggesting that total
apolipoprotein B is more predictive of cardiovascular events than non-
HDL cholesterol. Several methods are available for estimating total
apolipoprotein B. This study compared total
apolipoprotein estimated by immunonephelometric assay (INA), vertical auto profile (VAP), nuclear magnetic resonance (NMR), and non-
HDL cholesterol levels in patients with
hypertriglyceridemia from the previously reported
Simvastatin plus
Fenofibrate for Combined
Hyperlipidemia (SAFARI) trial. Total
apolipoprotein B levels were found to be highest by INA, intermediate by NMR and non-
HDL cholesterol, and lowest by VAP. Concordance for non-
HDL cholesterol levels among the INA, VAP, and NMR methods was better than that for total
apolipoprotein B levels; the correlation between non-
HDL cholesterol and
apolipoprotein B by INA was strongest (0.929). In patients with a low
triglyceride/HDL cholesterol ratio (<3.5), total
apolipoprotein B determined by INA was higher than that estimated from non-
HDL cholesterol levels, whereas in patients with a high
triglyceride/HDL C ratio (≥3.5),
apolipoprotein B predicted using non-
HDL cholesterol was in better agreement with INA-determined
apolipoprotein B levels. Similar trends were observed with VAP using equations specific for
LDL particle size. In conclusion, more work is needed to improve agreement of
apolipoprotein B measurements among methods employed clinically. Non-
HDL cholesterol is also useful to predict total
apolipoprotein B and some improvement may be attained by taking into account the ratio of
triglyceride/HDL cholesterol as a measurement of
LDL particle size.