ApoB/apoA-I ratio may improve CV risk prediction
MedWire News: The apolipoprotein (apo)B/A-I ratio may improve the predictive ability of low-density lipoprotein (LDL) cholesterol for detecting cardiovascular (CV) risk, Italian research suggests.
The team found that approximately 14% of patients with LDL cholesterol levels below 100 mg/dl (2.59 mmol/l) - the conventional target for lipid-lowering therapy in high CV risk patients - had an unfavorable apoB/A-I ratio.
Gian Paolo Fra (Università degli Studi del Piemonte Orientale, Corso Mazzini, Novara) and colleagues say that their findings suggest that LDL cholesterol alone is insufficient to define CV risk.
The authors recruited 616 glucose-tolerant individuals (273 men and 343 women), for whom measures of insulin resistance, lipid profiles, apoB/apoA-I ratio, and factors associated with the metabolic syndrome such as body mass index and waist circumference, were available.
Participants were divided into categories based on conventional cut-off values for LDL cholesterol: 100, 130, and 160 mg/dl (2.59, 3.37, and 4.14 mmol/l, respectively), and the proposed cut-off apoB/apoA-I ratios that define a high CV risk: up to 0.9 for men and 0.8 for women.
In all, 108 (17.5%) patients had LDL cholesterol levels below 100 mg/dl, and of these, 15 (13.9%) also had an unfavorable apoB/apoA-I ratio.
Fra et al report that, compared with patients with a favorable apoB/apoA-I ratio, those with an unfavorable ratio had more elements of the metabolic syndrome and their lipid profiles were strongly correlated with high CV risk.
For example, in the lowest and highest LDL cholesterol groups (<100 and ≥160 mg/dl), the respective HDL cholesterol levels were significantly lower in patients with an unfavorable apoB/apoA-I ratio compared with those with a favorable ratio, at 46.3 versus 55.3 mg/dl (1.20 vs 1.43 mmol/l) and 53.1 versus 60.3 mg/dl (1.38 vs 1.56 mmol/l).
The corresponding values for triglycerides, which were significantly higher in individuals with unfavorable apoB/apoA-I ratios compared with those with favorable ratios, were 142.4 versus 101.2 mg/dl (1.61 vs 1.14 mmol/l) and 146.8 versus 120.1 mg/dl (1.66 vs 1.36 mmol/l).
Writing in the journal Nutrition, Metabolism, and Cardiovascular Diseases, Fra et al say: "Together with LDL cholesterol, the apoB/apoA-I ratio adds further information about the effective CV risk: when this ratio is less than 0.9 (0.8 for females), the lipid profile is less atherogenic."
The team concludes, therefore, that the apoB/A-I ratio is at least complementary to LDL cholesterol for identifying the "effective" CV risk profile of asymptomatic normal glucose tolerant individuals.
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By Nikki Withers